Liquid crystal display element and method of producing the same

ABSTRACT

(1) A liquid crystal display element including a liquid crystal layer including liquid crystal contained between a pair of substrates and exhibiting a cholesteric phase, wherein an orientation film is arranged on at least one of the paired substrates, and is in contact with the liquid crystal layer, and liquid crystal molecular orientation processing for portions of each orientation film corresponding to pixel regions are effected in a manner different from that effected on at least a portion of a portion corresponding to non-pixel region of the orientation film on at least one of the substrates.  
     (2) A liquid crystal light modulation element including a liquid crystal layer held between a pair of substrate and including a liquid crystal material exhibiting a cholesteric phase in a room temperature and having a peak of a selective reflection wavelength in a visible wavelength range, wherein the liquid crystal layer in the selective reflection state has pixel regions neighboring to the opposite substrates, respectively, and liquid crystal domains in the pixel regions neighboring to at least one of the substrates are in a mixed state of a polydomain state and a monodomain state.

CROSS REFERENCE TO RELATED APPLICATION

[0001] The invention is based on patent application Nos. 2000-199023Pat., 2000-236810 Pat. 2001-72054 Pat., and 2001-72911 Pat. filed inJapan, the entire contents of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a liquid crystal displayelement, and in other words, a liquid crystal light modulation elementand method of producing the same.

[0004] 2. Description of the Background Art

[0005] The liquid crystal display element and, in other words, theliquid crystal light modulation element primarily includes a pair ofsubstrates, between which a liquid crystal layer including liquidcrystal material is held. For example, predetermined drive voltage isapplied to the liquid crystal layer to control orientation of liquidcrystal molecules in the liquid crystal layer so that external lightincident on the liquid crystal light modulation element is modulated toperform intended display of images or the like.

[0006] The liquid crystal light modulation element using the cholestericliquid crystal has been known as the above kind of liquid crystal lightmodulation element, and various studies have been made.

[0007] Examples of the cholesteric liquid crystal are, e.g., liquidcrystal, which exhibits the cholesteric phase by itself, and chiralnematic liquid crystal obtained by adding a chiral agent to nematicliquid crystal.

[0008] The cholesteric liquid crystal has such a feature that the liquidcrystal molecules form helical structures, and can exhibit three states,i.e., a planar state, focal conic state and a homeotropic state when itis held between a pair of substrates, and is subjected to an externalstimulus such as an electric field, a magnetic field or a heat.

[0009] In the liquid crystal light modulation element (e.g., liquidcrystal display element) using the cholesteric liquid crystal, thesethree states exhibit different light transparencies and reflectances.Therefore, the three states and the manner of applying the externalstimulus can be appropriately selected to perform the display. Forexample, the display may be performed in the cholesteric-nematic phasetransfer mode using the homeotropic state and the focal conic state, andmay be performed in a bistable mode using the planar state and the focalconic state.

[0010] Among them, the display in the bistable mode has such a featurethat the planar state and the focal conic state are stable even in thestate where no external stimulus is applied, and thus has thebistability (memory property), which maintains the display state evenwhen no external stimulus (e.g., voltage) is applied. For the abovereason, the liquid crystal light modulation element using thecholesteric liquid crystal has been increasingly studied in recent yearsas the memorizable element (display element achieving the stable displaystate).

[0011] In particular, the liquid crystal light modulation element usingthe cholesteric liquid crystal, which exhibits the selective reflectionproperty in the visible wavelength range when it is in the planar state,has the memorizable property, and can achieve a bright reflection state.In other words, it can perform bright display without using a polarizingplate or a color filter. Therefore, it is expected that the liquidcrystal light modulation element described above can be used as adisplay element, which is very effective at reducing the powerconsumption, and can be used as a display element of, e.g., a mobiletelephone requiring low power consumption.

[0012] The liquid crystal having the bistability can be stable in boththe planar state (i.e., the state of the planar orientation), where thehelical axis of the cholesteric liquid crystal is substantiallyperpendicular to the substrate surface, and the liquid crystal exhibitsthe selective reflection state, and the focal conic state (the state ofthe focal conic orientation), where the helical axis of the liquidcrystal is substantially parallel to the substrate surface, and theliquid crystal is transparent to the visible light.

[0013] However, in the liquid crystal display element utilizing theselective reflection characteristics of the cholesteric liquid crystal,the reflection wavelength shifts toward the shorter side in accordancewith the incident angle of the light and observation angle because itemploys the reflection manner using the light interference.

[0014] This phenomenon becomes more remarkable as the helical axis ofthe cholesteric liquid crystal in the planar orientation is closer tothe vertical direction to the substrate surface. In particular, a TNliquid crystal element and an STN liquid crystal element may use a pairof substrates having deposited and rubbed polyimide thin films thereonfor holding a liquid crystal layer therebetween, in which case thehelical axis of the cholesteric liquid crystal is perfectly orsubstantially perfectly perpendicular to the substrate surface,resulting in an extremely narrow view angle. If the above liquid crystalelement is used as the display element, therefore, the viewabilitybecomes extremely low.

[0015] The rubbing of the thin polyimide film increases the restrictingforce on a polyimide interface so that it becomes difficult to maintainthe focal conic state. Consequently, the bistability, which is thedistinctive feature of the cholesteric liquid crystal, may be lost.

[0016] For avoiding the above, it has been attempted to incline slightlythe helical axis of the cholesteric liquid crystal with respect to thenormal of the substrate. One of such attempts is called PSCT (PolymerStabilized Cholesteric Texture), in which polymers are dispersed in thecholesteric liquid crystal so that the helical axes may be positioned inrandom directions owing to mutual operations between the polymers andthe liquid crystal (U.S. Pat. No. 5,384,067). According to this method,however, mixing of the polymer in the liquid crystal material may lowerthe reliability of the element, and/or may require the increased drivevoltage.

[0017] In another method, a polyimide film not subjected to the rubbingis deposited on substrate surface opposed to the liquid crystal so thatthe helical axis may be inclined. In this method, however, domainsincluding different directions of the inclined helical axes (directionsof the helical axes projected onto the substrate) are formed randomly sothat scattering of the incident light is liable to occur due to thedifference in refractive index between the domains, resulting inlowering of the purity of the display color in the selective reflection.In a multilayer liquid crystal display element employing a multilayerstructure for multicolor display, the reflection light from the lowerlayer is liable to be affected by light scattering by an upper layer,which lowers both the contrast and color purity.

[0018] For improving the characteristics of the cholesteric liquidcrystal element, in which the liquid crystal is held between thesubstrates provided with the polyimide films not subjected to theorientation processing, Japanese Laid-open Patent Publication No.10-31205 (31205/1998) has disclosed the following manner. Differentsurface treatments are effected on the polyimide films formed on thesubstrates on the observation side and the non-observation (opposite)side, respectively. More specifically, the rubbing processing iseffected on only the polyimide film on the non-observation side, and theliquid crystal domains on the observation side may be thenon-orientation random domains (polydomain state). Thereby, the helicalaxes of the liquid crystal on the non-observation side may besubstantially perfectly perpendicular to the substrate surface, and theliquid crystal domains on the non-observation side may be uniform(mono-domain state).

[0019] According to this manner, however, the rubbing is effected on thewhole polyimide film area of the substrate on the non-observation side.Therefore, the liquid crystal domains form the monodomain state on thewhole substrate so that the stability in the focal conic state is liableto lower, and the bistability, which is the feature of the cholestericliquid crystal element, is may be impaired. In the planar orientationstate, the inclination of helical axes of the liquid crystal on therandom domain side is gradually lost, which impairs the long-termbistability. In any one of the above case, it is difficult to maintainthe display state (good display state with high contrast and colorpurity) for a long time without voltage application, and it is difficultto achieve the intended characteristics for high contrast and high colorpurity together with the bistability.

[0020] In the focal conic state of the cholesteric liquid crystal, thehelical axes of liquid crystal molecules are parallel to the substrateplane. Usually, the liquid crystal has a plurality of liquid crystalmolecule regions (liquid crystal domains). In the focal conic state, thehelical axes of the liquid crystal are parallel or substantiallyparallel to each other in each liquid crystal domain, but the directionsF′ of the helical axes in the neighboring liquid crystal domains are notparallel to each other as shown in FIG. 29. Accordingly, due to thedifference in refractive index between the liquid crystal domains, thelight incident on the liquid crystal element is slightly scattered at aninterface between the liquid crystal domains. In particular, if thehelical pitch is small (more specifically, if the helical pitch of theliquid crystal in the planar state is small to cause the selectivereflection in the visible range), the liquid crystal domains becomesmall in principle, and the light scattering occurs to a large extent inthe element so that employment thereof in the display element cause lowcontrast.

[0021] It is also known to use an element (multilayer liquid crystalelement) formed of a plurality of liquid crystal layers stacked togetherand, e.g., having different selective reflection wavelengths,respectively, for providing a multilayer liquid crystal light modulationelement, which allows color display in two or more colors (e.g., fullcolor display). In the case of this multilayer structure,multiple-scattering or the like between the liquid crystal layersparticularly increases the influence due to the scattering between thedomains so that the contrast is liable to be low.

[0022] In the display region of the liquid crystal display element(liquid crystal light modulation element), electrodes are not located onthe opposite sides of the liquid crystal in the region other than thepixels, and thus, the non-pixel region (the inter-pixel region).Therefore, the molecules of the liquid crystal in such region cannot becontrolled. This results in the following disadvantage.

[0023] If the liquid crystal between the substrates is in the planarstate (e.g., in the case where a multilayer liquid crystal displayelement is to be formed by stacking and adhering the plurality of liquidcrystal display elements under a pressure, and particularly the liquidcrystal between the substrates in each liquid crystal display element isin the planar state due to the pressure), a predetermined voltage may beapplied to the liquid crystal of the pixel(s) in one or more liquidcrystal display elements for changing the liquid crystal in the pixel(s)into the focal conic state, whereby the molecular orientation of theliquid crystal of the pixel(s) is controlled to attain the focal conicstate, as shown in FIG. 5. However, the liquid crystal between theneighboring pixels is affected by the applied voltage, and therebypartially attains the focal conic state so that the focal conic stateand the planar state are mixed in the liquid crystal between the pixels.In this mixed state, the domains of the different state may be adjacentto each other. In general, as compared with the case of only the planarstate alone, the domains are small in the case where the two states aremixed, and therefore incident light is liable to scatter. Further,selective reflection of the incident light may partially occur.

[0024] In the liquid crystal display element, a predetermined voltagemay be applied to the liquid crystal of the pixel for changing it fromthe focal conic state to the planar state. In this case, as shown inFIG. 6, the molecular orientation of liquid crystal of the pixel iscontrolled to attain the planar state. However, the liquid crystalbetween the neighboring pixels is affected by the applied voltage toattaint partially the planar state. Thus, the planar state and the focalconic state are mixed in the liquid crystal between the pixels.

[0025] For the above reasons, the planar state and the focal conic stateare mixed in the liquid crystal between the pixels in the liquid crystaldisplay element. In FIGS. 5 and 6, S indicates the substrate, Tindicates the electrode, Lc indicates the liquid crystal molecules, Pindicates the planar orientation state of the liquid crystal molecules,and F indicates the focal conic orientation state of the liquid crystalmolecules.

[0026] As described above, a part of the incident light is selectivelyreflected and scattered by the liquid crystal between the pixels due tomixing of the focal conic state and the planar state of the liquidcrystal between the pixels. This deteriorates the displaycharacteristics of the liquid crystal display element.

[0027] According to the study by the inventors, if the rubbingprocessing is not effected on the substrate surface or the like forcontrolling the orientation directions of the liquid crystal moleculesin the liquid crystal display element of the reflection type, the liquidcrystal molecules between the substrates tend to be positioned in therandom directions so that the view angle range allowing good observationof the display can be increased. This is already known.

[0028] However, if the rubbing processing is not effected for increasingthe view angle, the liquid crystal molecules between the pixels arepositioned in random directions. Therefore, the liquid crystal betweenthe pixels forms small domains, and light scattering is liable to occuron the boundary between the domains.

[0029] As described above, in the liquid crystal display element or inthe multilayer liquid crystal display element formed of the plurality ofliquid crystal layers stacked together, the incident light may bescattered or selectively reflected (R1 in FIG. 7) if the light isapplied to the liquid crystal between the pixels in each liquid crystaldisplay element without effecting no control on the molecularorientation, as shown in FIG. 7.

[0030] In the multilayer liquid crystal display element A′, as shown inFIG. 7, the liquid crystal in the non-pixel region on the upper side(image observation side), i.e., the liquid crystal in the regionsbetween the pixels scatters the light, which is selectively reflected bythe liquid crystal display element lower than the liquid crystal displayelement nearest to the observation side, and passes toward theobservation side (R2 in FIG. 7).

[0031] In this state, when performing the color display using thestacked liquid crystal display elements for display in red, green andblue, respectively, white display can be performed with high brightnessowing to the selective reflection and scattering by the liquid crystalin the non-pixel domains. However, when performing, e.g., the blackdisplay by a light absorbing layer Bk in the focal conic state of theliquid crystal in the pixels, the black display is blurred due to theselective reflection and scattering of the incident light by the liquidcrystal between the pixels, resulting in low contrast of the imagedisplay. Further, since the selective reflection and scattering of theincident light are caused by the liquid crystal between the pixels, andthe liquid crystal between the pixels scatters the light, which isselectively reflected by the lower layer toward the observation side,these lower the color purity in display.

[0032] In any one of the above cases, the optimum solution has not yetachieved in connection with the orientation control of the liquidcrystal in the above types of liquid crystal display element.

SUMMARY OF THE INVENTION

[0033] A primary object of the invention is to provide a liquid crystaldisplay element capable of image display with high quality.

[0034] Another object of the invention is to provide a liquid crystaldisplay element capable of image display with high contrast.

[0035] Still another object of the invention is to provide a liquidcrystal display element capable of image display with good color purity.

[0036] Yet another object of the invention is to provide a method ofproducing such an improved liquid crystal display element.

[0037] The invention provides the following liquid crystal displayelements (liquid crystal light (optical) modulation elements) andmethods of producing the same.

[0038] (1) Liquid Crystal Display Element (Liquid Crystal Light(Optical) Modulation Element)

[0039] (1-1) First Element

[0040] A liquid crystal display element including a liquid crystal layerincluding liquid crystal contained between a pair of substrates andexhibiting a cholesteric phase, wherein

[0041] an orientation film is arranged on at least one of the pairedsubstrates, and is in contact with the liquid crystal layer, and liquidcrystal molecular orientation processing for portions of eachorientation film corresponding to pixel regions is effected in a mannerdifferent from that effected on at least a portion of a portioncorresponding to non-pixel region (inter-pixel region) of theorientation film on at least one of the substrates.

[0042] The invention also provides a multilayer liquid crystal displayelement formed of the plurality of first liquid crystal display elementsstacked together.

[0043] (1-2) Second Element

[0044] A liquid crystal display element including a liquid crystal layerarranged between a pair of substrates and including liquid crystalexhibiting a cholesteric phase, and a plurality of pixels, wherein anorientation film is formed on at least one of the substrates, and liquidcrystal molecular orientation processing is effected on at least aportion of a portion corresponding to non-pixel region (inter-pixelregion) of the orientation film.

[0045] The invention also provides a multilayer liquid crystal displayelement formed of the plurality of second liquid crystal displayelements stacked together.

[0046] (1-3) Third Element

[0047] A liquid crystal display element formed of a plurality of liquidcrystal layers stacked together and each held between a pair ofsubstrates, wherein at least one of the plurality of liquid crystallayers is provided with an orientation film arranged on at least one ofthe paired substrates holding the liquid crystal layer therebetween andbeing in contact with the liquid crystal layer, and liquid crystalmolecular orientation processing for portions of each orientation filmcorresponding to pixel regions is effected in a manner different fromthat effected on at least a portion of a portion corresponding tonon-pixel region (inter-pixel region) of the orientation film on atleast one of the substrates.

[0048] The invention further provides fourth and fifth elements as wellas first and second element producing methods described later. These arebased on the following findings of the inventors.

[0049] In the liquid crystal light(optical) modulation element includinga pair of substrates and a liquid crystal layer held between thesubstrates and including a liquid crystal material, which exhibits acholesteric phase in a room temperature and has a peak of a selectivereflection wavelength in a visible wavelength range, a mixed state of apolydomain state and a monodomain state may be attained in the liquidcrystal domains of the pixel regions near at least one of the substratesholding the liquid crystal layer in the selective reflection state.Alternatively, the polydomain state may be achieved in each of theliquid crystal domains of the pixel regions near the substrates of theliquid crystal layer in the selective reflection state. Thereby, theliquid crystal in the liquid crystal domains in the pixel region nearone of the opposite substrates may have the cholesteric helical axesdifferent in angle with respect to a normal of the substrate from thatof the other substrate. Thereby, the reflected light can be collected onthe front surface on the element observation side, and the good imagedisplay with high brightness, contrast and color purity can beperformed. Further, when no external stimulus (e.g., no voltage) isapplied, the display state (image display with high brightness, contrastand color purity) can be maintained for a long term.

[0050] The above “polydomain state” is a bunch of domains, where thehelical axes of the liquid crystal in the selective reflection state areslightly inclined with respect to the substrate normal, and thedirections of the helical axes projected on the substrate are randomlydifferent among the domains. The “monodomain state” is a bunch ofdomains where the helical axes of the liquid crystal are perpendicularor substantially perpendicular to the substrate surface, and thus extendin a uniform direction.

[0051] (1-4) Fourth Element

[0052] A liquid crystal light(optical) modulation element including aliquid crystal layer held between a pair of substrates and including aliquid crystal material exhibiting a cholesteric phase in a roomtemperature and having a peak of a selective reflection wavelength in avisible wavelength range, wherein

[0053] the liquid crystal layer in a selective reflection state haspixel regions neighboring to the opposite substrates, respectively, andliquid crystal domains in the pixel regions neighboring to at least oneof the substrates are in a mixed state of a polydomain state and amonodomain state.

[0054] (1-5) Fifth Element

[0055] A liquid crystal light(optical) modulation element including aliquid crystal layer held between a pair of substrates and including aliquid crystal material exhibiting a cholesteric phase in a roomtemperature and having a peak of a selective reflection wavelength in avisible wavelength range, wherein

[0056] the liquid crystal layer in a selective reflection state haspixel regions neighboring to the opposite substrates, respectively, eachof liquid crystal domains in the pixel regions take a polydomain state,and angles of the cholesteric helical axes of the liquid crystal withrespect to the substrate normal are different between the liquid crystaldomains in the pixel regions near one of the opposite substrates and theliquid crystal domains in the pixel regions near the other substrate.

[0057] The invention also provides a liquid crystal light (optical)modulation element, in which a plurality of liquid crystals each heldbetween a pair of substrates are stacked, and at least one of theplurality of liquid crystal layers forms together with the correspondingpair of substrates holding the liquid crystal layer said fourth or fifthliquid crystal optical modulation element.

[0058] The inventors have also found such a phenomenon that scatteringbetween the domains is remarkably reduced by aligning the directions ofthe helical axes of the cholesteric liquid crystal molecules in thefocal conic state, and provides a sixth element and a third elementproducing method described later based on the above finding.

[0059] (1-6) Sixth Element

[0060] A liquid crystal light(optical) modulation element for performinglight (optical) modulation by utilizing a focal conic state of liquidcrystal molecules included in a liquid crystal layer held between a pairof substrates, wherein helical axes of the liquid crystal molecules inthe focal conic state extend in regular directions within a planesubstantially parallel to a substrate surface.

[0061] As an element of the same kind as the above, the inventionprovides a liquid crystal light(optical) modulation element forperforming light(optical) modulation by utilizing a focal conic state ofliquid crystal molecules included in a liquid crystal layer held betweena pair of substrates, wherein orientation regulating means for theliquid crystal molecules is employed for orientating the helical axes ofthe liquid crystal molecules in the focal conic state in regulardirections within a plane substantially parallel to a substrate surface.

[0062] The invention also provides a multilayer liquid crystal displayelement formed of the plurality of said liquid crystal opticalmodulation elements stacked together.

[0063] (2) Method of Producing Liquid Crystal Display Element (LiquidCrystal Light(Optical) Modulation Element)

[0064] (2-1) First Element Producing Method

[0065] A method of producing a liquid crystal light(optical) modulationelement including a liquid crystal layer held between a pair ofsubstrates and including a liquid crystal material exhibiting acholesteric phase at a room temperature and having a peak of a selectivereflection wavelength in a visible wavelength range, including:

[0066] a substrate processing step of processing at least one of thepaired substrates such that the liquid crystal layer in the selectivereflection state has pixel regions neighboring to the oppositesubstrates, respectively, and liquid crystal domains in the pixelregions neighboring to at least one of the substrates are in a mixedstate of a polydomain state and a monodomain state; and

[0067] a step of arranging the liquid crystal layer between the pairedsubstrates including the substrate(s) subjected to the substrateprocessing step.

[0068] (2-2) Second Element Producing Method

[0069] A method of producing a liquid crystal light(optical) modulationelement including a liquid crystal layer held between a pair ofsubstrates and including a liquid crystal material exhibiting acholesteric phase at a room temperature and having a peak of a selectivereflection wavelength in a visible wavelength range, including:

[0070] a substrate processing step of processing the paired substratessuch that the liquid crystal layer in the selective reflection state haspixel regions neighboring to the opposite substrates, respectively,liquid crystal domains in the pixel regions take a polydomain state, andthe angles of the cholesteric helical axes of the liquid crystal withrespect to the substrate normal are different between the liquid crystaldomains in the pixel regions near one of the opposite substrates and theliquid crystal domains in the pixel regions near the other substrate;and

[0071] a step of arranging the liquid crystal layer between the pairedsubstrates subjected to the substrate processing step.

[0072] (2-3) Third Element Producing Method

[0073] A method of producing a liquid crystal light(optical) modulationelement for performing light (optical) modulation by utilizing a focalconic state of liquid crystal molecules included in a liquid crystallayer held between a pair of substrates, including the steps ofproviding orientation regulating means (e.g., a projected structure, agroove in an electrode formed on the substrate, an insulating filmhaving a groove and formed on the substrate, a region on the substratehaving partially different orientation regulating force) for the liquidcrystal molecules for orientating helical axes of the liquid crystalmolecules in the focal conic state on at least one of the substrates;and a step of arranging the liquid crystal layer between the pairedsubstrates.

[0074] The foregoing and other objects, features, aspects and advantagesof the present invention will become more apparent from the followingdetailed description of the present invention when taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0075]FIG. 1 is a schematic cross section of an example of a three-layerliquid crystal display element.

[0076]FIG. 2 is a schematic plan showing a pixel pattern of one elementin the multilayer liquid crystal display element shown in FIG. 1.

[0077]FIG. 3 schematically shows a focal conic state of one element inthe three-layer liquid crystal display element shown in FIG. 1.

[0078]FIG. 4 schematically shows a planar state of the liquid crystaldisplay element shown in FIG. 3.

[0079]FIG. 5 schematically shows a focal conic state of a liquid crystaldisplay element in the prior art.

[0080]FIG. 6 schematically shows a planar state of a liquid crystaldisplay element in the prior art.

[0081]FIG. 7 is a schematic cross section of a three-layer liquidcrystal display element in the prior art.

[0082]FIG. 8 shows reflection characteristics of a liquid crystaldisplay element of an embodiment of the invention and a liquid crystaldisplay element in the prior art.

[0083]FIG. 9 is a schematic cross section of an example of a liquidcrystal light modulation element.

[0084]FIG. 10 is a schematic plan of a pixel pattern of the liquidcrystal light modulation element shown in FIG. 9.

[0085]FIG. 11(A) shows a liquid crystal layer in the selectivereflection state of the liquid crystal light modulation element shown inFIG. 9, and particularly shows a mixed state of polydomain state andmonodomain state of the liquid crystal in the pixel region opposed andneighboring to at least one of the substrates. FIG. 11(B) shows a liquidcrystal layer in the selective reflection state of the liquid crystallight modulation element shown in FIG. 9, and particularly shows a statewherein each of the liquid crystal domains in the pixel regions opposedand neighboring to the opposite substrates attains the polydomain stateand the liquid crystal in each of the liquid crystal domains opposed andneighboring to the opposite substrates has the cholesteric helical axesdifferent in angle with respect to a normal of the substrate from thatof the other substrate.

[0086]FIG. 12 shows a modified liquid crystal light modulation elementsimilar to that shown in FIG. 9, and particularly a state where rib-likeprojected structures forming an example of the orientation regulatingmeans is formed.

[0087]FIG. 13 shows a state where distortion occurs in equal potentiallines near the projected structure in the liquid crystal lightmodulation element provided with the rib-like projected structure.

[0088]FIG. 14 shows a state where an electric field direction partiallyinclined in a specific direction in the liquid crystal light modulationelement provided with the rib-lke projected structure.

[0089]FIG. 15 shows a state where helical axes of the liquid crystal areregularly positioned in a plane substantially parallel to the substrate.

[0090]FIG. 16 shows a top view of the liquid crystal light modulationelement, and particularly shows a state shown in FIG. 15.

[0091]FIG. 17 shows another modified liquid crystal light modulationelement similar to that shown in FIG. 9, and particularly shows a statewhere a groove (slit), i.e., another example of the orientationregulating means is formed on an electrode.

[0092]FIG. 18 shows a state where distortion occurs in equal potentiallines near a slit in the liquid crystal light modulation element havingan electrode provided with the slit.

[0093]FIG. 19 shows further another modified liquid crystal lightmodulation element similar to that shown in FIG. 9, and particularly anexample in which a partially processed region is formed on anorientation control layer (orientation film).

[0094] FIGS. 20(A)-20(D) show, by way of example, steps of producing aliquid crystal light modulation element, and FIG. 20(A) shows a step offorming an insulating film on an electrode surface of a substrateprovided with an electrode pattern, FIG. 20(B) shows a step of formingan orientation film on the insulating film, FIG. 20(C) shows a step ofexposing the orientation film with a light source through openings in amask, FIG. 20(C′) shows a step of forming a resist film on theorientation film, patterning the resist film and rubbing the orientationfilm through openings in the resist film, and FIG. 20(D) is a step ofremoving the resist film and obtaining partially processed regions.

[0095]FIG. 21 is a schematic cross section of a multilayer liquidcrystal light modulation element formed of three liquid crystal lightmodulation elements performing display in blue, red and green andlayered in this order.

[0096]FIG. 22 shows the multilayer liquid crystal light modulationelement shown in FIG. 21, and particularly a state where neighboringliquid crystal display elements have common substrates.

[0097]FIG. 23 shows view angle characteristics of a liquid crystal lightmodulation element obtained in an experimental example 1.

[0098]FIG. 24 shows view angle characteristics of liquid crystal lightmodulation elements obtained in an experimental example 2 and acomparative experimental example 1.

[0099]FIG. 25 shows view angle characteristics of a liquid crystal lightmodulation element obtained in a comparative experimental example 2.

[0100]FIG. 26 shows view angle characteristics of liquid crystal lightmodulation elements obtained in an experimental example 3 and theexperimental example 2.

[0101]FIG. 27 is chromaticity diagrams of images displayed by a liquidcrystal display element obtained in an experimental example 8 and acomparative example of a liquid crystal display element having threelayers of liquid crystal display elements each having oppositesubstrates not subjected to the rubbing.

[0102]FIG. 28 is a chromaticity diagram of an image displayed by aliquid crystal display element obtained in an experimental example 9.

[0103]FIG. 29 is a view showing directions of helical axes of respectiveliquid crystal domains in the focal conic state in a conventional liquidcrystal element.

[0104] FIGS. 30(a)-30(d) are cross sections showing a structure of aliquid crystal light modulation element.

[0105]FIG. 31 shows a distribution of equal potential lines by a projectstructure.

[0106]FIG. 32 shows an electric field distribution by an application ofvoltage.

[0107]FIG. 33 shows directions of helical axes of respective liquidcrystal domains in the focal conic state after removing the voltage.

[0108]FIG. 34 shows directions of helical axes of respective liquidcrystal domains in the focal conic state of the structure provided withorientation regulating means.

[0109]FIG. 35 shows a distribution of equal potential lines caused by agroove formed in an electrode.

[0110]FIG. 36 is a cross section of another structure of the liquidcrystal light modulation element.

[0111] FIGS. 37(a)-37(f) show by way of example steps of producing aliquid crystal light modulation element.

[0112] FIGS. 38(a)-38(g) show by way of example steps of producing aliquid crystal light modulation element.

[0113] FIGS. 39 (a)-39(d) show by way of example steps of producing aliquid crystal light modulation element.

[0114] FIGS. 40(a)-40(d) show by way of example steps of producing aliquid crystal light modulation element.

[0115] FIGS. 41(a)-41(c) show further different examples of theorientation regulating means.

[0116]FIG. 42 is a cross section showing a structure of a multilayerliquid crystal display element.

[0117]FIG. 43 is a cross section showing another structure of amultilayer liquid crystal display element.

[0118]FIG. 44 is a cross section showing still another structure of amultilayer liquid crystal display element.

[0119]FIG. 45 is a cross section showing further another structure of amultilayer liquid crystal display element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0120] (1) With Respect to First, Second and Third Liquid CrystalDisplay Element

[0121] (1-1) First Element

[0122] A first liquid crystal display element includes a liquid crystallayer including liquid crystal contained between a pair of substratesand exhibiting a cholesteric phase.

[0123] An orientation film is arranged on at least one of the pairedsubstrates, and is in contact with the liquid crystal layer, and liquidcrystal molecular orientation processing for portions of eachorientation film corresponding to pixel regions is effected in a mannerdifferent from that effected on at least a portion of a portioncorresponding to non-pixel region (inter-pixel region) of theorientation film on at least one of the substrates.

[0124] A multilayer liquid crystal display element may be formed of theplurality of first liquid crystal display elements stacked together.

[0125] In the liquid crystal display element and the multilayer liquidcrystal display element described above, the orientation film isarranged on one of or each of the paired substrates of the liquidcrystal display element, and is in contact with the liquid crystallayer. The liquid crystal molecular orientation processing for eachorientation film is performed such that the processing for portions ofeach orientation film corresponding to the pixel regions is effected ina manner different from that effected on at least a portion of theportion corresponding to non-pixel region of the orientation film on atleast one of the substrates (i.e., one or both of the orientation filmsin the case where the orientation films are arranged on both the pairedsubstrates, and one orientation film in the case where the orientationfilm is formed on only one substrate). Accordingly, the orientationprocessing for the orientation film portion corresponding to thenon-pixel region (inter-pixel region) can be performed independently,and thereby the molecular orientation of the liquid crystal between thepixels can be controlled so that the selective reflection of a part ofincident light by the liquid crystal between the pixels as well as thescattering of the incident light can be suppressed. In the liquidcrystal display element, the optical characteristics such as contrastcan be improved owing to the above.

[0126] In the multilayer liquid crystal display element, the selectivereflection of a part of incident light by the liquid crystal between thepixels as well as the scattering of the incident light can likewise besuppressed in each of the stacked elements. Further, such a situationcan be prevented that the light scattering by the liquid crystal betweenthe pixels in the liquid crystal display element on the upper side(image observation side) is caused when the light selectively reflectedby the liquid crystal display element, which is located at a lower levelthan the liquid crystal display element on the end of the imageobservation side, passes toward the observation side. Thereby, themonochrome (e.g., black and white) image display can be performed withgood contrast, and the color display can be performed with high colorimpurity.

[0127] For the orientation film provided on at least one of thesubstrates in the liquid crystal display element described above, theliquid crystal molecular orientation processing may be performed indifferent manners on the portions corresponding to the pixel regions andat least a portion of the portion corresponding to the non-pixel region(inter-pixel region) (i.e., regions between the pixels), respectively.

[0128] The orientation films may be arranged on the opposite substrates,respectively, in which case the liquid crystal molecular orientationprocessing for each orientation film may be performed in differentmanners on the portions corresponding to the pixel regions and at leasta portion of the portion corresponding to the non-pixel region,respectively.

[0129] The “liquid crystal molecular orientation processing ” alsoincludes a case where the orientation processing is not effected. Forexample, the orientation processing may not be effected on the portionscorresponding to the pixel regions of the orientation film, and theorientation processing may be effected on at least a portion of theportion corresponding to the non-pixel region.

[0130] (1-2) Second Liquid Crystal Display Element

[0131] As a liquid crystal display element having advantages similar tothe above, following element is provided.

[0132] A liquid crystal display element including a liquid crystal layerarranged between a pair of substrates and containing liquid crystalexhibiting a cholesteric phase, and a plurality of pixels, wherein anorientation film is formed on at least one of the substrates, and liquidcrystal molecular orientation processing is effected on at least aportion of a portion corresponding to non-pixel region (inter-pixelregion) of the orientation film.

[0133] The invention also provides a multilayer liquid crystal displayelement formed of the plurality of second liquid crystal displayelements stacked together.

[0134] (1-3) Third Element

[0135] As a liquid crystal display element having advantages similar tothe above, following mitilayer element is provided.

[0136] A liquid crystal display element formed of a plurality of liquidcrystal layers stacked together and each held between a pair ofsubstrates, wherein at least one of the plurality of liquid crystallayers is provided with an orientation film arranged on at least one ofthe paired substrates holding the liquid crystal layer therebetween andbeing in contact with the liquid crystal layer, and liquid crystalmolecular orientation processing for portions of each orientation filmcorresponding to pixel regions is effected in a manner different fromthat effected on at least a portion of a portion corresponding tonon-pixel region (inter-pixel region) of the orientation film on atleast one of the substrates.

[0137] In this element, it is not necessary that different substrates,which are dedicated to the neighboring liquid crystal layers,respectively, are arranged between the neighboring liquid crystallayers, and a common substrate may be arranged between the neighboringliquid crystal layers.

[0138] In this multilayer liquid crystal display element, the aboveorientation film may be employed for at least one (or only one) liquidcrystal layer.

[0139] The multilayer liquid crystal display element may be providedwith the orientation film arranged on at least one of the pairedsubstrates holding each of the liquid crystal layers, and liquid crystalmolecular orientation processing for portions of each orientation filmof each liquid crystal layer corresponding to pixel regions may beeffected in a manner different from that effected on at least a portionof a portion corresponding to non-pixel region (inter-pixel region) ofthe orientation film on at least one of the paired substrates.

[0140] In the orientation film arranged on at least one of the pairedsubstrates holding the liquid crystal layer therebetween, the liquidcrystal molecular orientation processing may be effected on the portionscorresponding to the pixel regions and at least a portion of the portioncorresponding to the non-pixel region in different manners,respectively.

[0141] The orientation films may be arranged on all the substratesurfaces opposed to each liquid crystal layer.

[0142] (1-4) Features Common to the First to Third Elements

[0143] In any one of the above elements, the orientation processingeffected on at least a portion of the portion corresponding to thenon-pixel region of the orientation film may be performed to set theliquid crystal of the inter-pixel region corresponding to theorientation-processed portion to the planar state.

[0144] The orientation processing of the orientation film may be rubbingprocessing or optical orientation processing.

[0145] If the processing is effected on at least a portion of theportion corresponding to the non-pixel region of the orientation film toset the liquid crystal of the inter-pixel region to the planar state,such setting can be achieved by horizontal orientation processingperformed by rubbing of the orientation film.

[0146] By setting the liquid crystal between the pixels to the perfector substantially perfect planar state providing large domains, thescattering of light at the boundary between the domains can besignificantly reduced. Since the liquid crystal molecules in the planarstate are orientated in the same direction, the light which is reflectedby the regular reflection is selectively reflected, and other lightpasses so that the selectively reflected light cannot be viewed on theimage observation side unless it is observed from a specific directionthat matches with the regular reflection.

[0147] In the case of the multilayer liquid crystal display element, thetransparency of the liquid crystal between the pixels can be increased,and the attenuation of the light reflected by the lower layer can bereduced when leading the light toward the image observation side.Therefore, the color image display of high quality can be performed.

[0148] From now on, the liquid crystal display elements will be improvedto attain higher resolutions and smaller pixel pitches. Therefore, therate of inter-pixel regions forming the non-pixel regions in the imagedisplay screen will increase. The above type of liquid crystal displayelements are advantageous in view of these facts.

[0149] (1-5) With respect to Image Display Elements Shown in Figures andOthers

[0150] The liquid crystal display elements of the foregoing types andothers will now be described with reference to FIGS. 1-8.

[0151]FIG. 1 is a schematic cross section of an example of themultilayer liquid crystal display element.

[0152] A multilayer liquid crystal display element A shown in FIG. 1 isformed of liquid crystal display elements B, G and R, which are employedfor display in blue, green and red, respectively. These elements B, Gand R are stacked in this order, and are adhered together by adhesivesN.

[0153] In the liquid crystal display element B, a liquid crystal layerLCB exhibiting a cholesteric phase for image display in blue is heldbetween a pair of transparent substrates SB1 and SB2 opposed together.

[0154] Each of substrates SB1 and SB2 is provided with electrodes TB1and TB2 on the surfaces opposed to the liquid crystal layer LCB,respectively. The electrode TB1 is formed of a plurality of thinbelt-like electrodes extending in the longitudinal direction of thesubstrate SB1. The electrode TB2 is likewise formed of a plurality ofthin belt-like electrodes extending parallel to the short side of thesubstrate SB2, and thus perpendicularly to the electrode TB1.

[0155] The substrates SB1 and SB2 are further provided with orientationfilms FB. The orientation film FB covers the electrodes, and is incontact with the liquid crystal layer LCB.

[0156] The liquid crystal layer LCB includes spacers SPB and resinstructures RCB. The spacers SPB and resin columns RCB maintain apredetermined space or distance between the opposite substrates.Elements G and R, which will be described later, employ similar spacersand resin columns for the same purpose as the above.

[0157] The liquid crystal layer LCB is surrounded by a seal wall SLB forsealing the periphery of the space between the substrates. The seal wallSLB is formed of, e.g., thermoplastic resin or thermosetting resin,although not restricted thereto.

[0158] In the liquid crystal display element G, a liquid crystal layerLCG exhibiting a cholesteric phase for image display in green is heldbetween a pair of transparent substrates SG1 and SG2 opposed together.

[0159] Each of substrates SG1 and SG2 is provided with electrodes TG1and TG2 on the surfaces opposed to the liquid crystal layer LCG,respectively. The electrode TG1 is formed of a plurality of thinbelt-like electrodes extending in the longitudinal direction of thesubstrate SG1. The electrode TG2 is likewise formed of a plurality ofthin belt-like electrodes extending parallel to the short side of thesubstrate SG2, and thus perpendicularly to the electrode TG1.

[0160] The substrates SG1 and SG2 are further provided with orientationfilms FG.

[0161] The liquid crystal layer LCG includes spacers SPG and resinstructures RCG.

[0162] The liquid crystal layer LCG is surrounded by a seal wall SLG forsealing the periphery of the space between the substrates.

[0163] In the liquid crystal display element R, a liquid crystal layerLCR exhibiting a cholesteric phase for image display in red is heldbetween a pair of transparent substrates SR1 and SR2 opposed together.

[0164] Each of substrates SR1 and SR2 is provided with electrodes TR1and TR2 on the surfaces opposed to the liquid crystal layer LCR,respectively. The electrode TR1 is formed of a plurality of thinbelt-like electrodes extending in the longitudinal direction of thesubstrate SR1. The electrode TR2 is likewise formed of a plurality ofthin belt-like electrodes extending parallel to the short side of thesubstrate SR2, and thus perpendicularly to the electrode TR1.

[0165] The substrates SR1 and SR2 are further provided with orientationfilms FR.

[0166] The liquid crystal layer LCR includes spacers SPR and resinstructures RCR.

[0167] The liquid crystal layer LCR is surrounded by a seal wall SLR forsealing the periphery of the space between the substrates.

[0168] A light absorber layer BK is arranged on the outer surface of theouter substrate SR2 of the element R.

[0169] The multilayer liquid crystal display element A may bemanufactured as follows.

[0170] First, for the liquid crystal display element B, the transparentsubstrate SB1, which is provided with the electrode TB1 and theorientation film FB, and is made of glass, resin or the like, isprepared. Also, the transparent substrate SB2, which is provided withthe electrode TB2 and the orientation film FB, and is made of glass,resin or the like, is prepared. In this operation, a predeterminedorientation processing is effected in advance on at least one of theorientation films on the substrates SB1 and SB2, and more specificallyis effected in advance on at least a portion of the orientation filmportion corresponding to the non-pixel region (in other words,inter-pixel region). In this example, the processing is effected on eachof the orientation film on the substrates SB1 and SB2. Thus, thepredetermined orientation processing is effected in advance on at leasta portion of the portion corresponding to the non-pixel region(inter-pixel region), which is not pixel region where the electrodes TB1and TB2 intersect with each other, on each of the orientation films FBformed on the substrates SB1 and SB2. This orientation processing willbe described later. The seal wall SLB is formed on the substrate SB2,and the spacers SPB are dispersed thereon. The seal wall SLB thus formedhas a height slightly larger than the intended final height. The spacersSPB may be mixed in the seal wall SLB. The seal wall SLB may be providedwith a liquid crystal inlet. Further the resin structures RCB are formedon one of the substrates.

[0171] The substrates SB1 and SB2 are bonded together at a predeterminedtemperature such that the surface of the substrate SB2 provided with theseal wall SLB is opposed to the substrate SB1.

[0172] In this bonding processing, the seal wall SLB and the resinstructures RCB are adhered to the substrate, and are compressed to havea predetermined height, which keeps the predetermined distance betweenthe substrates.

[0173] The liquid crystal LCB is supplied, e.g., by vacuum supply, intothe empty cell thus prepared through the inlet in the seal wall, andthen the inlet is closed to complete the element B.

[0174] The liquid crystal display elements G and R are produced in thesimilar manner. For the liquid crystal display element R, the blacklight absorber layer is formed on the side of the substrate SR2 remotefrom the liquid crystal layer.

[0175] After Producing the respective liquid crystal display elements B,G and R, the substrates SB2 and SG1 as well as the substrates SG2 andSR1 are layered and adhered together by the transparent adhesives N sothat the three-layer liquid crystal display element A is formed.

[0176] The pixel pattern of the liquid crystal display element B in themultilayer element A thus produced is shown in FIG. 2. FIGS. 3 and 4 arecross sections fragmentarily showing the liquid crystal display elementB. FIG. 3 shows the focal conic state achieved by voltage application,and FIG. 4 shows the planar state. For the sake of convenience,description will be given on the liquid crystal display element B.However, the following description relating to the electrode pattern aswell as the focal conic state and the planar state can be true also withrespect to the other elements G and R.

[0177] In FIG. 2, “GSB” indicates the pixel region defined by thecrossing portions of the electrodes TB1 and TB2, and “HGB” indicates anon-pixel region (inter-pixel region) between the pixel regions. In thenon-pixel region HGB, the orientation processing for orientating theliquid crystal molecules to the horizontal direction is effected on atleast one of the orientation films FB of the two substrates SB1 and SB2.Accordingly, the inter-pixel region completely or substantiallycompletely attains the planar state providing large domains. This willnow be described in greater detail with reference to FIGS. 3 and 4. Thehelical structures of the liquid crystal LCB are schematically depictedin these figures for showing the directions of the helical axes. In thepractical structure, the helical pitch is sufficiently smaller than thethickness between the substrates. In the non-pixel region HGB of theexample shown in FIGS. 3 and 4, the orientation processing is noteffected on the orientation film FB on the substrate SB1, but theorientation processing for orientating the liquid crystal molecules tothe horizontal direction is effected on the orientation film FB on thesubstrate SB2. Accordingly, in the liquid crystal LCB within thenon-pixel region HGB, the direction of the liquid crystal LCB near thesubstrate SB2 is restricted by the orientation film FB on the substrateSB2. This restricting force decreases as the position moves toward thesubstrate SB1. However, the liquid crystal LCB in the whole non-pixelregion HGB completely or substantially completely attains the planarstate providing large domains.

[0178] In the state where the liquid crystal between the substrates ofthe element B is in the planar state shown in FIG. 4, when apredetermined voltage is applied to the liquid crystal LCB of the pixelregion GSB for changing the liquid crystal LCB in the pixel region GSBto the focal conic state, the molecular orientation of the liquidcrystal LCB in the pixel region GSB is controlled to attain the focalconic state as shown in FIG. 3. However, the liquid crystal LCB in thenon-pixel region HGB is already subjected to the foregoing orientationprocessing effected to the corresponding portion of the orientation filmFB, and therefore is not affected by the application of the voltage sothat it maintains the planar state P. These domains are large, and thescattering of light on the boundary between the domains is reduced. Theliquid crystal LCB in the non-pixel region HGB is in the planar state,in which the directors are orientated in the same direction, so that thelight of the regular reflection is selectively reflected, and the otherlight passes therethrough so that selectively reflected light cannot beviewed unless it is observed from specific direction that matches withthe regular reflection. The selectively reflected light can not beobserved when the incident direction of the external light to the liquidcrystal display element and the observation direction exhibit apredetermined relationship. Thereby, by slightly changing theobservation position, the selectively reflected right can be easilyavoided. The above can be true also with respect to the elements G andR. Owing to the above, each of elements B, G and R can reduceunnecessary scattering and selective reflection, and can improve theoptical characteristics such as contrast.

[0179] Each element can improve the contrast when used in the liquidcrystal display element for monochrome (monocolor) display.

[0180] In the multilayer liquid crystal display element A, the lighttransparency of the liquid crystal in the non-pixel region can beincreased, and the reflected light coming from the lower layer can beled toward the image observation side while suppressing the attenuation.Thereby, the color image display of high quality can be achieved.

[0181] In the multilayer liquid crystal display element, the substrateslocated between the liquid crystal layers of the neighboring liquidcrystal display elements may be formed of the substrate common to boththe liquid crystal layers.

[0182] Further specific examples of the multilayer liquid crystaldisplay element A of the type shown in FIG. 1 will now be described.

Example 1

[0183] This example is a three-layer liquid crystal display element ofthe reflection type using glass substrates, in which the rubbingprocessing is effected on a portion of each orientation film in eachliquid crystal display element corresponding to the liquid crystal inthe non-pixel region.

[0184] The liquid crystal display elements B, G and R were produced inthe foregoing methods, and then were successively layered and bonded bythe adhesives N.

[0185] In each element, 7059 glass substrate (manufactured by CorningInc.) was used as each substrate. On each substrate, belt-liketransparent ITO electrodes were formed in parallel with each other. Thebelt-like electrodes had a width of 300 μm, and were arranged with apitch of 340 μm.

[0186] On all the surfaces of the substrates in contact with the liquidcrystal, there were formed the orientation films made of polyimideAL8044 (manufactured by JSR Corp.) Rubbing processing was effected on aportion of each orientation film corresponding to the non-image region(inter-pixel region).

[0187] The rubbing processing was effected in the following manner.First, resist of about 1 μm in thickness was uniformly applied by atable coater over the polyimide film formed on the substrate. The resistwas of the positive type. Then, a photomask of the same configuration asthe electrode pattern was arranged on the substrate coated with theresist, and exposure was performed by an exposing device. After theexposure, development was performed to remove the resist from thenon-pixel region, and the resist remained on only the electrode pattern.In this state, the rubbing processing was performed using a knownrubbing processing method. After the rubbing processing, the resist wasremoved.

[0188] In this manner, the rubbing processing was effected on thestructure while leaving the resist on only the electrode pattern.Thereby, the portion of the orientation film corresponding to thenon-pixel region (inter-pixel region) was subjected to the orientationprocessing except for the portions corresponding to the electrodes. Therubbing processing was not effected on the orientation film portioncorresponding to the pixel region either. In this example, as describedabove, the orientation processing was effected in different manners onthe portions corresponding to the pixel regions of the orientation filmand at least a portion of the portion corresponding to the non-pixelregion.

[0189] The substrates thus processed were bonded together so that thesubstrates could be parallel to each other, and the parallel ITOelectrodes on one side of the liquid crystal could be perpendicular tothe electrodes on the other side.

[0190] The liquid crystal filling the lower, middle and upper liquidcrystal display elements were cholesteric selective-reflection liquidcrystal, which could selectively reflect the light in red, green andblue, respectively. The liquid crystal for red display was made ofcholesteric liquid crystal, which had a peak wavelength of the selectivereflection equal to 680 nm, and was made of a mixture of nematic liquidcrystal BL46 and 32.6 wt % of chiral agent CB15 both manufactured byMerk & Co. The liquid crystal for green display was made of cholestericliquid crystal, which had a peak wavelength of the selective reflectionequal to 550 nm, and was made of a mixture of nematic liquid crystalBL46 and 40 wt % of chiral agent CB15 both manufactured by Merk & Co.The liquid crystal for blue display was made of cholesteric liquidcrystal, which had a peak wavelength of the selective reflection equalto 480 nm, and was made of a mixture of nematic liquid crystal BL46 and47.6 wt % of chiral agent CB15 both manufactured by Merk & Co.

[0191] Spacers N3M14 (manufactured by Ube-Nitto Kasei Co., Ltd.), whichwere made of thermoplastic resin and had a particle diameter of 7 μm,were arranged between the substrates at dispersion density of about 200pcs/mm². Also, resin structures, which were made of polyester resinPES-360S30 (manufactured by Three Bond Co., Ltd.) and had a diameter ofabout 40 μm and a height of 7 μm, were formed with a pitch of 300 μm.The seal wall provided with the liquid crystal inlet was made of thesame polyester resin as the above. The inlet was closed byultraviolet-curing resin Photolec A-704-60 (manufactured by SekisuiFinechemical Co., Ltd.) after supply of the liquid crystal.

[0192] Black paint forming the light absorber layer was applied to theouter surface of the outer substrate of the liquid crystal displayelement for red display.

[0193] Black display was performed by the three-layer liquid crystaldisplay element of the cholesteric selective reflection type, in whichthe rubbing processing was effected on the polyimide orientation filmportion corresponding to the non-pixel region, as described above. As aresult, the light scattering and selective reflection were reduced inthe inter-pixel region of each liquid crystal display element, andY-value (luminous reflectance) lowered to increase the contrast. In thecolor display operation, the color purity could be higher than that ofthe structure, in which the rubbing processing was not effected on theorientation film portion corresponding to the non-pixel region.

Example 2

[0194] In each liquid crystal display element, the orientation film,which could be subjected to optical orientation processing, was formedon each of the substrate surfaces in contact with the liquid crystal,and the optical orientation processing was effected on the film portioncorresponding to the non-pixel region. Structures other than the abovewere the same as those of the example 1.

[0195] The optical orientation was performed in the following manner.First, a photomask of the same configuration as the electrode patternwas arranged on the substrate, which was coated with polyimide, i.e.,the orientation film material similar to that of the example 1, and wasregistered with the electrode pattern on the substrate. The abovestructure was irradiated with ultraviolet light. A lamp for emitting theultraviolet light was a mercury lamp having a central wavelength of 365nm. The emitting direction of the ultraviolet light formed 75° withrespect to the normal of the substrate. The irradiation intensity was500 mJ/cm², and a deflector plate for deflecting the ultraviolet lightwas attached to the photomask.

[0196] Black display was performed by the three-layer liquid crystaldisplay element of the cholesteric selective reflection type, in whichthe orientation processing was effected to control and keep theorientation of the liquid crystal in the non-pixel region in the planarstate, as described above. As a result, the light scattering andselective reflection were reduced in the inter-pixel region, and Y-valuelowered to increase the Y-value ratio (contrast) (Y-value in whitedisplay/Y-value in black display). In the color display operation, thecolor purity could be higher than that of the structure, in which therubbing processing was not effected on the orientation film portioncorresponding to the non-pixel region.

Example 3

[0197] A plurality of substrates of 0.2 μm in thickness, made ofpolycarbonate manufactured by Teijin Limited, were employed. Eachsubstrate was provided with transparent belt-like ITO electrodesparallel to each other. Each transparent electrode had a width of 300 μmand was arranged with a pitch of 330 μm.

[0198] All the surfaces of each substrate in contact with the liquidcrystal were provided with polyimide films AL8044 manufactured by JSRCorp., and the rubbing processing was effected in the following manneron the portion of the polyimide film in the non-pixel region.

[0199] First, positive resist of about 1 μm in thickness was uniformlyapplied to the polyimide film by a table coater. A photomask providedwith holes of configurations corresponding to the electrode pattern wasarranged on the substrate coated with the resist, and the exposure bythe exposing device was performed. By the development after theexposure, the resist between the pixels, i.e., the resist in thenon-pixel region was removed, and the resist was left on only theelectrodes. In this state, the rubbing processing was effected in theknown rubbing method. After the rubbing processing, the resist wasremoved.

[0200] The substrates thus processed were arranged so that thesubstrates could be parallel to each other, and the parallel ITOelectrodes on one side of the liquid crystal could be perpendicular tothe electrodes on the other side.

[0201] The liquid crystal filling the lower, middle and upper liquidcrystal display elements could selectively reflect the light in red,green and blue, respectively. The liquid crystal for red display wasmade of cholesteric liquid crystal, which had a peak wavelength of theselective reflection equal to 680 nm, and was made of a mixture ofnematic liquid crystal BL46 and 32.6 wt % of chiral agent CB15 bothmanufactured by Merk & Co. The liquid crystal for green display was madeof cholesteric liquid crystal, which had a peak wavelength of theselective reflection equal to 550 nm, and was made of a mixture ofnematic liquid crystal BL46 and 40 wt % of chiral agent CB15 bothmanufactured by Merk & Co. The liquid crystal for blue display was madeof cholesteric liquid crystal, which had a peak wavelength of theselective reflection equal to 480 nm, and is made of a mixture ofnematic liquid crystal BL46 and 47.6 wt % of chiral agent CB15 bothmanufactured by Merk & Co.

[0202] Spacers N3M14 (manufactured by Ube-Nitto Kasei Co., Ltd.), whichwere made of thermoplastic resin and had a particle diameter of 5 μm,were arranged between the substrates at dispersion density of about 400pcs/mm². Also, resin structures, which were made of polyester resinPES-360S30 (manufactured by Three Bond Co., Ltd.) and had a diameter ofabout 50 μm and a height of 5 μm, were formed with a pitch of 500 μm.The seal wall provided with the liquid crystal inlet was made of thesame polyester resin as the above. The inlet was closed byultraviolet-curing resin Photolec A-704-60 (manufactured by SekisuiFinechemical Co., Ltd.) after supply of the liquid crystal.

[0203] Black display was performed by the three-layer liquid crystaldisplay element of the selective reflection type, in which the rubbingprocessing was effected on the polyimide orientation film portioncorresponding to the non-pixel region, as described above. As a result,the light scattering and selective reflection were reduced in theinter-pixel region of each liquid crystal display element. As comparedwith the structure not subjected to the rubbing processing, Y-value(luminous reflectance) was larger by 0.68 times, and the contrast wasimproved by 2.0 points. In the color display operation, the color puritycould be higher than that of the structure, in which the rubbingprocessing was not effected on the orientation film portioncorresponding to the non-pixel region.

[0204] For confirming the performances of the liquid crystal displayelements of the types described above, test pieces were prepared in thefollowing manner, and the Y-values and reflectances were measured.First, a pattern of ITO, which had an electrode portion of 10 mm by 10mm forming the pixel and a terminal potion for connection to a powersource, was formed on each of glass substrates, and a polyimide film wasarranged on the ITO. Some of the polyimide films thus prepared werealready subjected to the rubbing processing, and the others are notsubjected to the rubbing processing. Liquid crystal was vacuum-suppliedinto a space between the two substrates subjected to the rubbingprocessing so that a liquid crystal layer of 5 μm in thickness was heldtherebetween to form a sample A. Another liquid crystal layer of 5 μm inthickness was held between the two substrates not subjected to therubbing processing in a similar manner so that a sample B was formed.

[0205] The above liquid crystal was made of cholesteric liquid crystal,which had a peak wavelength of the selective reflection equal to 550 nm,and was made of a mixture of nematic liquid crystal BL46 and 40 wt % ofchiral agent CB15 both manufactured by Merk & Co. A light absorber layerwas arranged on the side of each sample remote from the observationside.

[0206] The luminous reflectance and Y-value were measured with aspectrometer CM-3700 manufactured by Minolta Co., Ltd.

[0207] For the sample A, the liquid crystal was set in the planar state,and the measurement was performed under the conditions that the regularreflection was removed. For the sample B, the measurement was performedfor the liquid crystal in the planar state and the liquid crystal in thefocal conic state under the conditions that the regular reflection wasremoved. In each of the samples, the planar state was achieved byapplying a pressure. The focal conic state of the sample B was achievedby applying a voltage to the liquid crystal from the liquid crystaldisplay element.

[0208] Result of the measurement are shown in Table 1 and FIG. 8. TABLE1 Sample Rubbing State Take-In Y-value Ref* A Yes Planar No 1.5 g1 B NoPlanar No 29.4 g2 C No F/C* No 6.9 g3

[0209] As can be seen from the Y-value and the reflectancecharacteristics g1 of the sample A, which was subjected to the rubbingprocessing and was in the planar state, the reflectance is extremelysmall, the reflection is suppressed to a higher extent than the sampleB, which was not subjected to the rubbing processing, in the planarstate and further the sample B in the focal conic state.

[0210] Thereby, it can be understood that, unless it is observed fromspecific direction that matches with the regular reflection, the clearblack display and high contrast can be achieved by effecting theorientation processing on the orientation film portion located betweenthe pixels, and thereby completely setting the liquid crystal locatedbetween the pixels to the planar state, as compared with the situationthat the orientation processing is not effected on the inter-pixelregion, and the planar state and the focal conic state are present in amixed state.

[0211] (2) With Respect to Fourth and Fifth Liquid Crystal DisplayElements (Liquid Crystal Light (Optical) Modulation Elements) and Firstand Second Methods of Producing the Elements

[0212] (2-1) Fourth Liquid Crystal Light (Optical) Modulation Element

[0213] This liquid crystal light (optical) modulation element includes aliquid crystal layer held between a pair of substrates and including aliquid crystal material exhibiting a cholesteric phase in a roomtemperature and having a peak of a selective reflection wavelength in avisible wavelength range.

[0214] In this element, the liquid crystal layer in the selectivereflection state has pixel regions neighboring to the oppositesubstrates, respectively, and liquid crystal domains in the pixelregions neighboring to at least one of the substrates are in a mixedstate of a polydomain state and a monodomain state.

[0215] (2-2) Fifth Liquid Crystal Light(Optical) Modulation Element

[0216] A liquid crystal light(optical) modulation element includes aliquid crystal layer held between a pair of substrates and including aliquid crystal material exhibiting a cholesteric phase in a roomtemperature and having a peak of a selective reflection wavelength in avisible wavelength range.

[0217] In this element, the liquid crystal layer in the selectivereflection state has pixel regions neighboring to the oppositesubstrates, respectively, liquid crystal domains in the pixel regionstake a polydomain state, and the angles of the cholesteric helical axesof the liquid crystal with respect to the substrate normal are differentbetween the liquid crystal domains in the pixel regions near one of thesubstrates and the liquid crystal domains in the pixel regions near theother substrate.

[0218] In each of the fourth and fifth liquid crystal light(optical)modulation elements, at least one of the paired substrates is usuallytransparent, and the substrate on the observation side is usuallytransparent.

[0219] The above “polydomain” is a bunch of domains, where the helicalaxis of the liquid crystal in the selective reflection state is slightlyinclined with respect to the substrate normal, and the directions of thehelical axes projected onto the substrate are randomly different amongthe domains. The “monodomain” is a bunch of domains where the helicalaxes of the liquid crystal are perpendicular or substantiallyperpendicular to the substrate surface, and thus extend in a uniformdirection.

[0220] In the fourth liquid crystal optical modulation element, theliquid crystal layer in the selective reflection state has pixel regionsneighboring to the opposite substrates, respectively, and the liquidcrystal domains of the pixel regions neighboring to at least one of thesubstrates is in a mixed state of a polydomain state and a monodomainstate. In the fifth liquid crystal optical modulation element, theliquid crystal layer in the selective reflection state has pixel regionsneighboring to the opposite substrates, respectively, and the liquidcrystal domains in the pixel regions take a polydomain state, and anglesof cholesteric helical axes of the liquid crystal with respect to thesubstrate normal are different between the liquid crystal domains in thepixel regions near one of the substrates and the liquid crystal domainsin the pixel regions near the other substrate (thus, the angle of thehelical axis of the liquid crystal domain in the pixel region near oneof the substrates with respect to the substrate normal is smaller thanthat of the pixel region near the other substrate). Therefore, goodimage display with high brightness, contrast and color purity can beperformed, and the display state with high brightness, contrast andcolor purity can be maintained for a long time, e.g., even when thevoltage is not applied. In other words, the characteristics of highreflection intensity, high contrast and high color purity in the planarstate can be achieved together with the bistability.

[0221] In the fourth and fifth liquid crystal optical modulationelements, electrodes (e.g., pixel electrodes) may be formed on thepaired substrates, if necessary.

[0222] In the selective reflection state of the fourth liquid crystaloptical modulation element, the liquid crystal domains in the pixelregions near the opposite substrates may be in the foregoing mixedstate. Also, the liquid crystal domains in the pixel regions near one ofthe substrates may be in the foregoing mixed state, and the liquidcrystal domains in the pixel regions near the other substrate may takeonly the polydomain state.

[0223] In the selective reflection state, if each of the liquid crystaldomains in the pixel regions near the opposite substrates is in theforegoing mixed state, it is preferable that a ratio between the liquidcrystal domains taking polydomain state and the liquid crystal domainstaking monodomain state is different between the liquid crystal domainin each of the pixel regions near one of the substrates and the liquidcrystal domain in each of the pixel regions near the other substrate. Itis further preferable that the liquid crystal domain in each of thepixel regions near the substrate on an element observation side take thepolydomain state at a higher rate than that on the other side.

[0224] In the selective reflection state, if the liquid crystal domainsin each of the pixel regions near one of the substrates are in theforegoing mixed state, and the liquid crystal domains in each of thepixel regions near the other substrate take only the polydomain state,it is preferable that the liquid crystal domains in the pixel regionsnear the substrate on the element observation side take only thepolydomain state.

[0225] In any case of the fourth element, an orientation control layermay be arranged at least on the substrate opposed to the liquid crystaldomains in the mixed state, and particularly on the side of thesubstrate opposed to the liquid crystal domains in the mixed state, andmay be in contact with the liquid crystal. Thereby, the liquid crystalmolecules in the mixed state may be subjected to the orientation controlby the orientation control layer. This orientation control may beperformed in the following manners (a) and (b).

[0226] (a) The orientation control is performed by the rubbing, which iseffected on the orientation control layer arranged on the substrateopposed to the liquid crystal domains in the mixed state. In this case,it is preferable that the orientation control layer subjected to therubbing has a rubbing density of 10 or lower. For example, by performingthe rubbing through a mask having a predetermined opening pattern, theorientation control layer can be partially subjected to the rubbing sothat the foregoing mixed state may be achieved.

[0227] The direction of the rubbing is not restricted, and the rubbingcan be performed in any direction. For example, in the case where thebelt-like electrodes are arranged on the substrate, the rubbing may beperformed either parallel to or perpendicular to the electrodes.However, in the case of effecting the rubbing on the whole orientationcontrol layer, the rubbing is performed in a single direction.

[0228] (b) The orientation control is performed by emitting light underpredetermined condition(s) to the orientation control layer, which isarranged on the substrate opposed to the liquid crystal domains in themixed state. The above predetermined conditions may contain any one ofthe amount of emitted light, the substrate temperature, the angle of theincident light on the substrate surface. More specifically, theorientation control may be performed by the amount of the emitted light,may be performed by the substrate temperature during the irradiation ofthe orientation control layer with the predetermined light, or may beperformed by the angle of the predetermined light emitted to theorientation control layer with respect to the substrate surface. Thelight irradiation may be performed with a mask having a predeterminedpattern of openings so that the orientation control layer is partiallyirradiated with the light for achieving the foregoing mixed state. Inany one of the above cases, the predetermined light may be ultravioletlight. In the case where the monodomain state and polydomain state arepresent in the mixed fashion, the average angle of the liquid crystalhelical axes with respect to the substrate is preferably in a rangelarger than zero and not exceeding 10°, and more preferably in a rangefrom 3° to 8°.

[0229] In the fifth liquid crystal optical modulation element, it ispreferable in the selective reflection state that the liquid crystal ofthe liquid crystal domains in the pixel region near the substrate on theobservation side has the cholesteric helical axes, which define a largerangle with respect to the substrate normal than that of the liquidcrystal in the liquid crystal domains remote from the observation side.

[0230] In any one of the foregoing cases, the fifth liquid crystaloptical modulation element may be provided with the orientation controllayers, which are provided on the sides of the paired substrates opposedto the liquid crystal layer, respectively, and are in contact with theliquid crystal, so that the orientation control layers may control theangles of the cholesteric helical axes of the liquid crystal in therespective liquid crystal domains of the pixel regions near the oppositesubstrates with respect to the substrate normal in the selectivereflection state. As a result of the control by the orientation controllayer, a difference occurs in the angle of the cholesteric helical axisof the liquid crystal with respect to the substrate normal between theliquid crystal domains in the pixel regions near the oppositesubstrates. As examples of the difference in angle, the following cases(c) and (d) will now be described.

[0231] (c) The difference is caused by the fact that at least one of theorientation control layers arranged on the opposite substrates issubjected to the rubbing. It is desired that the rubbing density of theorientation control layer does not exceed 10. The difference in anglemay be caused, e.g., by partially effecting the rubbing on theorientation control layer through a mask having a predetermined patternof openings. In any one of the above cases, the orientation controllayer may not change into the monodomains, depending on the material ofthe orientation film and/or rubbing conditions, and the polydomainshaving the helical axes at a smaller angle than the original angle areobtained.

[0232] (d) The difference is caused by the fact that at least one of theorientation control layers which are arranged on the oppositesubstrates, respectively, is irradiated with light under thepredetermined condition(s).

[0233] The predetermined conditions may include the amount of emittedlight, substrate temperature, incident angle of the light on thesubstrate surface. More specifically, the difference, which is presentin the angle of the cholesteric helical axis of the liquid crystal tothe substrate normal between the liquid crystal domains in the pixelregions near the opposite substrates, may be controlled by the amount ofthe predetermined light emitted to the orientation control layer, thetemperature of the substrate during irradiation of the orientationcontrol layer with the predetermined light, or the incident angle of thepredetermined light with respect to the substrate surface duringirradiation of the orientation control layer with the predeterminedlight. For example, the irradiation with the light may be performedthrough a mask having a predetermined pattern of openings so that theorientation control layer may be partially irradiated with the light,whereby the difference in angle may be caused as described above. In anyone of the above cases, the orientation control layer may not changeinto monodomains depending on the material of the orientation filmand/or the irradiation conditions, and the polydomains having thehelical axes, of which inclination is smaller than the originalinclination, are obtained. In any one of the above cases, thepredetermined light may be ultraviolet light.

[0234] In the cases (c) and (d), the inclination of the helical axes ofthe liquid crystal molecules in the region of the orientation controllayer, which is subjected to the rubbing processing or lightirradiation, becomes lower than that of the other region, although itdoes not become perpendicular. Owing to this, the average inclination ofthe helical axes of the whole liquid crystal molecules probably becomessmaller than that before the processing.

[0235] The fifth liquid crystal optical modulation element may beprovided with the orientation control layers, which are provided on thesides of the paired substrates opposed to the liquid crystal layer,respectively, and are in contact with the liquid crystal, so that theorientation control layers may control the angles of the cholesterichelical axes of the liquid crystal in the respective liquid crystaldomains of the pixel regions near the opposite substrates with respectto the substrate normal in the selective reflection state. In this case,material parameters of the orientation control layers provided for theopposite substrates may be different from each other. In this case, theorientation control layers provided on the opposite substrates andhaving different material parameters control the angles of thecholesteric helical axes of the liquid crystal in the liquid crystaldomains of the pixel regions near one of the substrates and the liquidcrystal domains of the pixel regions near the other substrate withrespect to the substrate normal. The orientation control layers may bemade of different materials, respectively, so that the materialparameter of each orientation control layer is different from the other.The material parameter may be a pretilt angle, although not restrictedthereto. As will be described later, the orientation control layer maybe partially made of a different material for controlling the aboveangle.

[0236] In the selective reflection state of any one of the fourth andfifth liquid crystal optical modulation elements, the angle of thecholesteric helical axis of the liquid crystal in each of the liquidcrystal domains of the pixel regions near the opposite substrates withrespect to the substrate normal maybe preferably 20°or less on average,and more preferably may be 20°or less in all the liquid crystal domains.If this angle exceeds 20°, the bistability already described isdeteriorated.

[0237] According to the study by the inventors, it is already foundthat, in a liquid crystal optical modulation element for performingoptical modulation by utilizing a focal conic state of liquid crystalmolecules included in a liquid crystal layer held between a pair ofsubstrates, scattering between the domains is remarkably reduced byaligning the directions of the helical axes of the cholesteric liquidcrystal molecules in the focal conic state.

[0238] By orientating helical axes of the liquid crystal molecules inthe focal conic state in regular directions within a plane substantiallyparallel to a substrate surface, the light transparency of the liquidcrystal layer in the focal conic state is remarkably improved, and thecontrast can be improved.

[0239] Accordingly, in the fourth and fifth liquid crystal opticalmodulation elements, the helical axes of the liquid crystal molecules inthe focal conic state may be arranged in regular directions within aplane substantially parallel to the substrate surface. Thereby, thehelical axes of the liquid crystal molecules in the focal conic stateare orientated, and the light scattering in the element is reduced.

[0240] In this case, orientation regulating means for the liquid crystalmolecules may be employed in the liquid crystal element for aligning ororientating helical axes of the liquid crystal molecules in the focalconic state in regular directions within a plane substantially parallelto a substrate surface.

[0241] The orientation regulating means may be a region providedpartially on a surface of at least one of the substrates in contact withthe liquid crystal, and having a different orientation regulating force.This region can regularly orientate the helical axes of the liquidcrystal. By employing the region of a different orientation regulatingforce, the helical axes are orientated by the difference in surfaceregulating force during transition of the liquid crystal molecules tothe focal conic state. Thereby, the helical axes of the liquid crystalcan be regularly orientated.

[0242] The region providing the different orientation regulating forcemay be formed by rubbing or light irradiation. It may be also formed,e.g., by the method of partially effecting the rubbing, partiallyperforming light irradiation or employing a partially differentmaterial.

[0243] The manners of entirely or partially effecting the rubbing andthe manners of entirely or partially effecting the light irradiation maybe similar to those employed in the fourth liquid crystal opticalmodulation element, if it is provided with the foregoing orientationcontrol layer, and the liquid crystal molecules in the foregoing mixedstate of the liquid crystal layer in the selective reflection state aresubjected to the orientation control by the orientation control layer.The manners of entirely or partially effecting the rubbing, the mannersof entirely or partially effecting the light irradiation and the mannerof employing a partially different material may be similar to thoseemployed in the fifth liquid crystal optical modulation element of theinvention, if it is provided with the orientation control layer, and theorientation control layer controls the angle of the cholesteric helicalaxis of the liquid crystal in each of the liquid crystal domains of thepixel regions near the opposite substrates with respect to the substratenormal when the liquid crystal layer is in the selective reflectionstate.

[0244] In the fourth liquid crystal optical modulation element,therefore, the mixed state where the monodomain state and the polydomainstate are mixed is achieved, and the focal conic state causing lesslight scattering can be achieved. In the fifth liquid crystal opticalmodulation element, the partial rubbing processing, partialphoto-orientation processing or use of a partially different materialmay be employed for causing a difference in inclination of the helicalaxes, in which case the focal conic state causing less light scatteringcan be achieved.

[0245] More specifically, the fourth liquid crystal optical modulationelement has a region of a different orientation regulating force, whichcauses monodomain state and polydomain state. Therefore, it can beconsidered that, when the liquid crystal molecules change to the focalconic state, the above region regularly orientates the helical axes ofthe liquid crystal owing to the difference in surface regulating force,and thereby the scattering in the focal conic state can be reduced. Inthe fifth liquid crystal optical modulation element, although thepartial rubbing processing, partial photo-orientation processing or useof a partially different material does not provide the completemonodomain regions, but the inclination of the helical axis in each ofthe minute regions is different from the others. Therefore, it can beconsidered that, when the liquid crystal molecules change to the focalconic state, the above region regularly orientates the helical axes ofthe liquid crystal owing to the difference in surface regulating force,and thereby the scattering in the focal conic state can be reduced.

[0246] Assuming that the region of the different orientation regulatingforce has a width of W, and the liquid crystal has a helical pitch of P,it is preferable that the following relationship is present between thewidth W and the pitch P.

P<W<20P

[0247] Assuming that the regions of different orientation regulatingforce are arranged at a pitch of L, and the liquid crystal has thehelical pitch of p, it is preferable that the following relationship ispresent between the arrangement pitch L and the helical pitch p.

5p<L<100p

[0248] By employing the regions of the different orientation regulatingforce having the width W and arrangement pitch L in the foregoingranges, a good regulating force can be kept for the liquid crystalmolecules, and complication of the element producing process can beprevented.

[0249] The arrangement pitch of the regions of the different orientationregulating force may not be uniform within the above range. By employingthe arrangement pitch of the regions of the different orientationregulating force, which is not uniform, it is possible to preventlowering of the visibility due to light diffraction.

[0250] In any one of the cases described above, a plurality of pixelsmay be arranged in the display region. In this case, the direction ofthe arrangement of the regions of the different orientation regulatingforce may be different from that of the arrangement direction of thesepixels. A plurality of regions, which are different in the arrangementdirection of the regions of the different orientation regulating force,may be employed. In these cases, the visibility is not affected by thelight incident angle, and uniform light transparent characteristics canbe achieved.

[0251] In the fourth and fifth liquid crystal optical modulationelements, the helical axes of the liquid crystal molecules in the focalconic state may be aligned in regular directions within a planesubstantially parallel to a substrate surface, in which case the liquidcrystal material exhibiting the cholesteric phase at the roomtemperature may be a material having positive dielectric anisotropy.

[0252] In connection with the fourth and fifth liquid crystal opticalmodulation elements, a multilayer liquid crystal light (optical)modulation element can be provided, which is formed of a plurality ofliquid crystal layers stacked together and each held between the pairedsubstrates, and at least one of the liquid crystal layers and thecorresponding pair of substrates holding the liquid crystal form thefourth or fifth liquid crystal optical modulation element.

[0253] In this multilayer liquid crystal optical modulation element, theplurality of liquid crystal layers may be formed of liquid crystallayers, which perform display in different colors, and thus havedifferent peak wavelengths of the selective reflection, respectively,whereby multicolor display (i.e., display in two or more colors) can beperformed. At least three liquid crystal layers, which perform displayin blue, green and red, respectively, may be employed for full-colordisplay. Two liquid crystal layers having different optical rotationdirections may be employed, in which case the light utilizing efficiencycan be increased. The liquid crystal layers of different opticalrotation directions may have the substantially same peak wavelength ofthe selective reflection, in which case the light reflectance of theliquid crystal layer can be increased.

[0254] In any one of the above cases, the above multilayer liquidcrystal optical modulation element may be a multilayer liquid crystaloptical modulation element formed of a plurality of liquid crystalelements including at least one or all formed of the fourth or fifthtypes of liquid crystal elements. The neighboring liquid crystal opticalmodulation elements may commonly use the same substrate between theneiboring liquid crystal layers.

[0255] Any one of the multilayer liquid crystal optical modulationelements may employ the following preferable forms.

[0256] (e) In any neighboring liquid crystal optical modulationelements, the angle of the cholesteric helical axis of the liquidcrystal in the liquid crystal domains of each of the pixel regions nearthe substrate on the observation side in the liquid crystal opticalmodulation element in the selective reflection state on the elementobservation side with respect to the substrate normal is larger than theangle of the cholesteric helical axis of the liquid crystal in theliquid crystal domains of each of the pixel regions near the substrateon the observation side in the liquid crystal optical modulation elementin the selective reflection state on the side opposite to the elementobservation side with respect to the substrate normal.

[0257] (f) In any neighboring liquid crystal optical modulationelements, the angle of the cholesteric helical axis of the liquidcrystal in the liquid crystal domains of each of the pixel regions nearthe substrate on the side opposite to the observation side in the liquidcrystal optical modulation element in the selective reflection state onthe element observation side with respect to the substrate normal islarger than the angle of the cholesteric helical axis of the liquidcrystal in the liquid crystal domains of each of the pixel regions nearthe substrate opposite to the observation side in the liquid crystaloptical modulation element in the selective reflection state on the sideopposite to the element observation side with respect to the substratenormal.

[0258] (g) Combination of the above (e) and (f)

[0259] In any one of the above cases, each of the liquid crystal opticalmodulation elements of the multilayer liquid crystal optical modulationelement may include the orientation control layer arranged on thesubstrate opposed to the liquid crystal domains in the mixed state ofthe polydomain state and monodomain state, and subjected to the rubbing,in which case it is preferable in any neighboring liquid crystal opticalmodulation elements that the rubbing density of the orientation controllayer subjected to the rubbing and arranged in the liquid crystaloptical modulation element on the element observation side is smallerthan the rubbing density of the orientation control layer, correspondingto the above orientation control layer, subjected to the rubbing andarranged in the liquid crystal optical modulation element on theopposite side.

[0260] The multilayer liquid crystal optical modulation element maycontain a liquid crystal layer, in which the liquid crystal molecules inthe focal conic state have the helical axes arranged regularly in aplane substantially parallel to the substrate surface. In this case, atleast the liquid crystal layer on the outermost side (elementobservation side) may be the liquid crystal layer, in which the liquidcrystal molecules in the focal conic state have the helical axesarranged regularly in a plane substantially parallel to the substratesurface. In any one of the above cases, it can be effectively suppressedthat the light transparency increases in the focal conic state due toincrease of the scattering components by layering of the plurality ofliquid crystal layers.

[0261] As examples of the method of producing the liquid crystal light(optica) 1 modulation element described above, first and secondproducing methods described below may be employed. The contents alreadydescribed in connection with the fourth and fifth liquid crystal opticalmodulation elements can be true also with respect to the first andsecond producing methods as well as the liquid crystal opticalmodulation elements produced by the first and second methods.

[0262] (2-3) First Method of Producing Liquid Crystal Light(Optical)Modulation Element

[0263] A first method is a method of producing a liquid crystallight(optical) modulation element including a liquid crystal layer heldbetween a pair of substrates (usually including at least one transparentsubstrate), and containing a liquid crystal material exhibiting acholesteric phase at a room temperature and having a peak of a selectivereflection wavelength in a visible wavelength range.

[0264] This method includes a substrate processing step of processing atleast one of the paired substrates such that the liquid crystal layer inthe selective reflection state may have pixel regions neighboring to theopposite substrates, respectively, and liquid crystal domains in thepixel regions neighboring to at least one of the substrates may be in amixed state of a polydomain state and a monodomain state; and

[0265] a step of arranging the liquid crystal layer between the pairedsubstrates including the substrate(s) subjected to the substrateprocessing step.

[0266] (2-4) Second Method of Producing Liquid Crystal Light(Optical)Modulation Element

[0267] A second method is a method of producing a liquid crystallight(optical) modulation element including a liquid crystal layer heldbetween a pair of substrates (usually including at least one transparentsubstrate), and containing a liquid crystal material exhibiting acholesteric phase at a room temperature and having a peak of a selectivereflection wavelength in a visible wavelength range.

[0268] This method includes a substrate processing step of processingthe paired substrates such that the liquid crystal layer in theselective reflection state may have pixel regions neighboring to theopposite substrates, respectively, each of liquid crystal domains in thepixel regions may take a polydomain state, and the angles of thecholesteric helical axes of the liquid crystal with respect to thesubstrate normal may be different between the liquid crystal domains inthe pixel regions near one of the opposite substrates and the liquidcrystal domains in the pixel regions near the other substrate; and

[0269] a step of arranging the liquid crystal layer between the pairedsubstrates subjected to the substrate processing step.

[0270] In the first method of producing the liquid crystal opticalmodulation element, the substrate processing step is performed toprocess at least one of the paired substrates such that the liquidcrystal layer in the selective reflection state may have pixel regionsneighboring to the opposite substrates, respectively, and the pixelregions neighboring to one of the substrates may be in a mixed state ofa polydomain state and a monodomain state; and the step is performed forarranging the liquid crystal layer between the paired substratesincluding the substrate(s) subjected to the substrate processing step.In this manner, the fourth liquid crystal optical modulation elementdescribed above can be produced.

[0271] In the second method of producing the liquid crystal opticalmodulation element, the substrate processing step is performed toprocess the paired substrates such that the liquid crystal layer in theselective reflection state may have pixel regions neighboring to theopposite substrates, respectively, liquid crystal domains in the pixelregions may take a polydomain state, and the angles of the cholesterichelical axes of the liquid crystal with respect to the substrate normalmay be different between the liquid crystal domains in the pixel regionsnear one of the substrates and the liquid crystal domains in the pixelregions near the other substrate; and the step is performed forarranging the liquid crystal layer between the paired substratessubjected to the substrate processing step. In this manner, the fifthliquid crystal optical modulation element described above can beproduced.

[0272] The first and second Producing methods can provide the liquidcrystal optical modulation elements, in which good image display withhigh brightness, contrast and color purity can be performed, and thedisplay state with high brightness, contrast and color purity can bemaintained for a long time, e.g., even when the voltage is not applied.In other words, it is possible to provide the liquid crystal opticalmodulation elements, in which the characteristics of high reflectionintensity, high contrast and high color purity in the planar state canbe achieved together with the bistability.

[0273] In the first method of producing the liquid crystal opticalmodulation element, the substrate processing step maybe performed suchthat each of the liquid crystal domains in the pixel regions near theopposite substrates may be in the foregoing mixed state, or that theliquid crystal domains in the pixel regions near one of the substratesmay be in the foregoing mixed state, and the liquid crystal domains inthe pixel regions near the other substrate may take only the polydomainstate.

[0274] In the case where the processing is performed to attain the mixedstate in each of the liquid crystal domains in the pixel regions nearthe opposite substrates, it is preferable that a ratio between theliquid crystal domains taking polydomain state and the liquid crystaldomains taking monodomain state is different between the liquid crystaldomains in the pixel regions near one of the substrates and liquidcrystal domains in the pixel regions near the other substrate. It isfurther preferable that the liquid crystal domains in the pixel regionsnear the substrate on the element observation side take the polydomainstate at a higher rate than that on the other side.

[0275] In the case where the processing is performed to attain the mixedstate in the liquid crystal domains in the pixel regions near one of thesubstrates and to provide the other liquid crystal domains formed ofonly the polydomains, it is preferable that the mixed state is achievedin the liquid crystal domains in the pixel regions near the substrate onthe side opposite to the element observation side, and the liquidcrystal domains in the pixel regions near the substrate on the elementobservation side take only the polydomain state.

[0276] In the first method of producing the first liquid crystal opticalmodulation element, the substrate processing step may include a step ofproviding an orientation control layer on the side opposed to the liquidcrystal domains in the mixed state of at least one of the pairedsubstrates opposed to the liquid crystal domains in the mixed state; anda rubbing processing step of effecting rubbing processing on theorientation control layer arranged on the substrate opposed to theliquid crystal domains in the mixed state. In this case, it is desiredin the rubbing step that the orientation control layer is rubbed at arubbing density of 10 or less. The rubbing may be performed, e.g.,through a mask having a predetermined pattern of openings so that therubbing is partially effected on the orientation control layer forachieving the foregoing mixed state.

[0277] The substrate processing step may include a step of providing anorientation control layer on the side opposed to the liquid crystaldomains in the mixed state of at least one of the substrates opposed tothe liquid crystal domains in the mixed state; and a light irradiationstep of irradiating the orientation control layer arranged on thesubstrate opposed to the liquid crystal domains in the mixed state withpredetermined light for orientation control. In the light irradiatingstep, the amount of the predetermined light emitted to the orientationcontrol layer may be changed, the temperature of the substrate duringirradiation of the orientation control layer with the predeterminedlight may be changed, or the incident angle of the predetermined lightwith respect to the substrate surface during irradiation of theorientation control layer with the predetermined light may be changed.For example, the irradiation with the light may be performed through amask having a predetermined pattern of openings so that the orientationcontrol layer may be partially irradiated with the light, whereby themixed state described above may be achieved in the element. In any oneof the above cases, the predetermined light may be ultraviolet light.

[0278] In the substrate processing step, the processing conditions(e.g., the extent of rubbing in the rubbing processing step; and theamount of light irradiation, the substrate temperature during lightirradiation, or the light incident angle to the substrate surface in thelight emitting step) can be selected to control the view angle of theproduced liquid crystal optical modulation element.

[0279] According to the second method of producing the liquid crystaloptical modulation element, the substrate processing step may beperformed such that the angle of the cholesteric helical axis of theliquid crystal in the liquid crystal domain of each of the pixel regionsnear the substrate on the observation side with respect to the substratenormal in the selective reflection state is larger than the angle of thecholesteric helical axis of the liquid crystal in the liquid crystaldomain of each of the pixel regions near the opposite substrate withrespect to the substrate normal in the selective reflection state.

[0280] In any one of the above cases, according to the second method ofproducing the liquid crystal optical modulation element, the substrateprocessing step may include a step of providing orientation controllayers on the sides opposed to the liquid crystal layer of said pairedsubstrate; and a rubbing processing step of effecting rubbing processingon at least one of the orientation control layers arranged on theopposite substrates. In this case, it is desired in the rubbing stepthat the orientation control layer is rubbed at a rubbing density of 10or less. The rubbing may be performed, e.g., through a mask having apredetermined pattern of openings so that the rubbing is partiallyeffected on the orientation control layer for achieving the foregoingmixed state.

[0281] The substrate processing step may include a step of providingorientation control layers on the sides opposed to the liquid crystallayer of the paired substrates; and a light irradiation step ofirradiating at least one of the orientation control layers arranged onthe opposite substrates with predetermined light under predeterminedconditions. The above predetermined conditions maybe, e.g., the amountof irradiation light, substrate temperature or the incident angle of thelight to the substrate surface. More specifically, in the light emittingstep, the amount of the predetermined light emitted to the orientationcontrol layer may be changed, the temperature of the substrate duringirradiation of the orientation control layer with the predeterminedlight may be changed, or the incident angle of the predetermined lightwith respect to the substrate surface during irradiation of theorientation control layer with the predetermined light may be changed.For example, the irradiation with the light may be performed through amask having a predetermined pattern of openings so that the orientationcontrol layer may be partially irradiated with the light, whereby themixed state described above may be achieved in the element. In any oneof the above cases, the predetermined light may be ultraviolet light.

[0282] The substrate processing step may include a step of providing theorientation control layers exhibiting different material parameters onthe sides opposed to the liquid crystal layer of the oppositesubstrates. In this case, the orientation control layers may be made ofdifferent materials, respectively, so that the material parameter ofeach orientation control layer is different from the other. The materialparameter may be a pretilt angle, although not restricted thereto. Theorientation control layer may be partially made of a different materialfor controlling the above angle.

[0283] In the substrate processing step, the processing conditions(e.g., the extent of rubbing in the rubbing processing step; and theamount of light irradiation in the light emitting step, the substratetemperature during light irradiation; the light incident angle to thesubstrate surface in the light emitting step; or the selection of thematerial of the orientation control layer in the case of including thestep of arranging the respective orientation control layers to providedifferent material parameters) can be selected to control the view angleof the produced liquid crystal optical modulation element.

[0284] According to the first and second methods of producing the liquidcrystal optical modulation element, the substrate processing step may bepreferably performed such that the angle of the cholesteric helical axisof the liquid crystal in each of the liquid crystal domains of the pixelregions near the opposite substrates with respect to the substratenormal is 20° or less on average, and more preferably may be 20° or lessin all the liquid crystal domains.

[0285] The first and second methods of producing the liquid crystaloptical modulation element may include a step of partially arranging aregion providing a different orientation regulating force on the surfacein contact with the liquid crystal of at least one of the substrates fororientating regularly the helical axes of the liquid crystal moleculesin the focal conic state, and a step of arranging the liquid crystallayer between the paired substrates including at least one substrateprovided with the region having the different orientation regulatingforce.

[0286] According to this method, the form, position, arrangement pitch,orientation direction and others can be arbitrarily determined whenforming the region having the orientation regulating force. Accordingly,the orientation regulation of the liquid crystal can be easilycontrolled. A step for providing an independent member for regulatingthe orientation of the liquid crystal is not required.

[0287] in the step of partially providing the region having theorientation regulating force, the region may be formed by entirely orpartially effecting the rubbing, or In any one of the above cases, thestep of partially providing the region having the orientation regulatingforce may include a step of arranging a mask layer partially providedwith an opening on the substrate, and a step of removing the mask layer.

[0288] In the step of partially providing the region having theorientation regulating force, the orientation film partially made of adifferent material may be formed to provide the region of the differentorientation regulating force.

[0289] As the manner of entirely or partially effecting the rubbing aswell as the manner of entirely or partially effecting the lightirradiation described above, similar manner to those executed in therubbing processing step in the first and second methods of producing theliquid crystal optical modulation element can be employed. As the mannerof using the partially different material, similar manner to thatemployed in the second method for arranging the orientation controllayers providing the different material parameters on the sides of thepaired substrates opposed to the liquid crystal layer can be employed.

[0290] (2-5) With Respect to Liquid Crystal Light (Optical) ModulationElements Shown in Figures and Others

[0291] The liquid crystal optical modulation elements and others of thetypes already described will now be described with reference to FIGS. 9to 29.

[0292]FIG. 9 is a schematic cross section of an example of a liquidcrystal light (optical) modulation element.

[0293] The liquid crystal light modulation element shown in FIG. 9includes a pair of substrates 1 and 2 as well as a liquid crystal layer10 held therebetween. The liquid crystal layer 10 contains a liquidcrystal material 6, which exhibits a cholesteric phase at a roomtemperature, and has a peak of a selective reflection wavelength in avisible wavelength range. Resin structures 4 and spacers 5 are arrangedbetween the substrates 1 and 2 for keeping a space between thesubstrates 1 and 2. The resin structures 4 also function to couple thesubstrates together.

[0294] A visible light absorber layer is arranged, if necessary, on anouter surface (rear surface) of the substrate opposite to an elementobservation side P (light incident side). In the example shown in FIG.9, a visible light absorber layer 3 is arranged on the outer surface(rear surface) of the substrate 2. For example, the substrate 2 may beformed of a black substrate so that the substrate itself may have alight absorbing function.

[0295] S indicates a seal member for keeping the liquid crystal material6 between the substrates 1 and 2.

[0296] In the liquid crystal light modulation element shown in FIG. 9, apredetermined voltage is applied for switching the liquid crystal 6between the planar state (selective reflection state) and the focalconic state.

[0297] At least one of the substrates 1 and 2 in this example has lighttransparency. The substrate having the light transparency may be a glasssubstrate. Instead of the glass, the flexible substrate may be made of,e.g., polycarbonate, polyether sulfone (PES) or polyethyleneterephthalate. In the case where the liquid crystal light modulationelement is used as a liquid crystal light modulation element of thereflection type, such a structure is not required that both thesubstrates are transparent. In this example, both the substrates 1 and 2have the light transparency.

[0298] In liquid crystal light modulation elements including that shownin FIG. 9, electrodes may be formed on the pair of substrates, ifnecessary.

[0299] The electrode may be formed of a transparent conductive film madeof ITO (Indium Tin Oxide) or the like, a metal electrode made of, e.g.,aluminum or silicon, or a photoconductive film made of, e.g., amorphoussilicon or BSO (Bismuth Silicon Oxide). The electrodes formed on thesubstrate, which is used for holding the liquid crystal layer, have apredetermined pattern, and are used as the electrodes for controllingthe liquid crystal display element. The electrodes may have such apattern that a plurality of belt-like forms extend in parallel with eachother. The paired substrates carrying the electrodes of the belt-likepattern are opposed to each other with their electrodes locatedperpendicular to each other. Thus, the liquid crystal light modulationelement can use the electrode structure of a simple matrix form.Further, it is possible to use an electrode structure of an activematrix type, which includes a plurality of pixel electrodes andthin-film transistors connected thereto.

[0300] Instead of arranging the above electrode member on the substrate,which is used for holding the liquid crystal layer, an electrode, whichserves also as the substrate by itself, can be used as the substratemember.

[0301]FIG. 10 is a schematic plan of a pixel pattern of the liquidcrystal light modulation element shown in FIG. 9.

[0302] In the liquid crystal light modulation element shown in FIG. 9,as already described, the substrates 1 and 2 have light transparency,and these transparent substrates 1 and 2 are provided at their surfaceswith electrode groups, respectively, each of which includes a pluralityof belt-like parallel electrodes 11 or 12. The transparent electrodes 11and 12 are opposed and perpendicular to each other so that regions,where these electrodes 11 and 12 intersect, form pixel regions X,respectively (see FIG. 10).

[0303] The liquid crystal light modulation element shown in FIG. 9 aswell as other liquid crystal optical modulation elements may be providedwith gas barrier layers and/or insulating layers, each of which may beformed of an insulating film having a function of improving reliabilityof the liquid crystal light modulation element. The insulating film maybe made of a material selected from various organic and inorganicmaterials. In this example, insulating films 7 are arranged on theelectrodes 11 and 12, respectively.

[0304] In addition to the liquid crystal material 6, such a liquidcrystal material may be employed in liquid crystal light modulationelement that exhibit a cholesteric phase when held between a pair ofsubstrates (e.g., substrates with electrodes). For example, cholestericliquid crystal having a cholesterol ring may be used. In addition to theabove, it is possible to use a nematic liquid crystal having an opticalactive group, or liquid crystal prepared by adding a chiral agent tocholesteric liquid crystal or nematic liquid crystal. These materials(nematic liquid crystal, cholesteric liquid crystal and chiral agent)may be used solely, or may be used as a mixture of two or more kinds ofthe materials.

[0305] The liquid crystal having a peak of the selective reflectionwavelength in the visible wavelength range may be cholesteric liquidcrystal having the helical pitch, which is effective at reflecting thelight in the visible wavelength range by itself. In addition to theabove, such a liquid crystal may be used that is prepared by adding anappropriate amount of material having an optical active group materialto the nematic liquid crystal material for controlling the helicalpitch.

[0306] In general, the visible wavelength range is not strictly defined,and is slightly variable depending upon varied ideas. The visiblewavelength range determined in the embodiments may be in a range whichis generally considered as the visible wavelength range. In theembodiments and experimental examples, which will be described later,the visible wavelength range is between 400 nm and 700 nm. In the liquidcrystal light modulation element of the cholesteric selective reflectiontype, scattered components are included in a shorter wavelength rangethan the selective reflection wavelength range. For absorbing thescattered components and improving the color purity, dye(s) absorbingthe light in the shorter wavelength range than the selective reflectionwavelength range may be added to the liquid crystal material.

[0307]FIG. 11(A) and 11(B) show examples of the respective liquidcrystal domains in pixel regions X opposed and neighboring to thesubstrates 1 and 2 of the liquid crystal layer 10 of the liquid crystallight modulation element shown in FIG. 9 in the selective reflectionstate. FIGS. 11(A) and 11(B) do not show the insulating film 7 andothers.

[0308] In the liquid crystal light modulation element shown in FIG. 9,either of the following states is attained in the respective liquidcrystal domains in the pixel regions X opposed and neighboring to thesubstrates 1 and 2 of the liquid crystal layer 10 in the selectivereflection state.

[0309] (1) A mixed state of the polydomain state and monodomain state isattained in the respective liquid crystal domains in pixel regions X ofat least one of portions 1 a and 2 a opposed to the substrates 1 and 2of the liquid crystal layer 10 in the selective reflection state.

[0310] (2) A polydomain state is attained in each of the pixel regions Xof the portions 1 a and 2 a opposed to the substrates 1 and 2 of theliquid crystal layer 10 in the selective reflection state, and angles θ1and θ2 are different, which are defined by cholesteric helical axes 61and 62 of the liquid crystal with respect to a substrate normal H in theliquid crystal domains in the pixel regions X of the substratevicinities 1 a and 2 a, respectively, (see FIG. 11(B)).

[0311] The above “polydomain” is a bunch of domains, where the helicalaxis of the liquid crystal in the selective reflection state is slightlyinclined with respect to the substrate normal, and the projectiondirections of the helical axes with respect to the substrate arerandomly different. The “monodomain” is a bunch of domains where thehelical axes of the liquid crystal are perpendicular or substantiallyperpendicular to the substrate surface, and thus are extended in auniform direction.

[0312] The above case (1) will now be described with reference to FIG.11(A). The liquid crystal domains of the pixel region X of one of theopposite substrate vicinities 1 a and 2 a are in the mixed state(including monodomain state indicated by “M” in FIG. 11(A)), and theliquid crystal domains of the other substrate vicinity take only thepolydomain state. More specifically, the mixed state is attained in theliquid crystal domains in the pixel region X of the substrate vicinity 2a remote from the element observation side P, and the liquid crystaldomains in the pixel region X of the substrate vicinity 1 a on theelement observation side P take only polydomain state.

[0313] An orientation control layer 82, which is opposed to the liquidcrystal domain and is in contact with the liquid crystal 6, is arrangedon the side of the substrate 2 opposed to the liquid crystal domain inthe mixed state. The orientation of the crystal molecules 60 in themixed state is controlled by the orientation control layer 82. Thisorientation control may be performed in the following manners (a) and(b).

[0314] (a) The orientation control can be performed by the rubbing,which is effected on the orientation control layer 82 arranged on thesubstrate 2 opposed to the liquid crystal domain in the mixed state. Inthis case, it is desired that the orientation control layer 82 subjectedto the rubbing has a rubbing density of 10 or lower. For example, byperforming the rubbing through a mask having a predetermined openingpattern, the orientation control layer can be partially subjected to therubbing so that the foregoing mixed state may be achieved.

[0315] (b) The orientation control is performed by emitting light underpredetermined conditions to the orientation control layer 82, which isarranged on the substrate 2 opposed to the liquid crystal domain in themixed state. The orientation control may be determined, e.g., by theamount of the predetermined emitted light, the substrate temperatureduring the irradiation with the predetermined light, the angle of theincident light on the substrate surface or combination two or morethereof. For example, the light irradiation may be performed with a maskhaving a predetermined pattern of openings so that the orientationcontrol layer is partially irradiated with the light for achieving theforegoing mixed state. In any one of the above cases, the predeterminedlight may be ultraviolet light.

[0316] In this embodiment, the orientation control is performed byrubbing the orientation control layer 82 arranged on the substrate 2opposed to the liquid crystal domain in the mixed state. The rubbingdensity of the orientation control layer 82 thus subjected to therubbing is 10 or less.

[0317] An orientation control layer 81 is arranged on the side of thesubstrate 1 opposed to the liquid crystal domain formed of only thepolydomains. The orientation control layer 81 is made of the samematerial as the orientation control layer 82, but is not subjected tothe rubbing.

[0318] Description will now be given on the above case (2) withreference to FIG. 11(B). with respect to the substrate normal H, thecholesteric helical axis 61 of the liquid crystal 6 in the liquidcrystal domain of the pixel region X in the substrate vicinity 1 a onthe element observation side P forms the angle θ1 larger than the angleθ2, which is formed with respect to the substrate normal H by thecholesteric helical axis 62 of the liquid crystal 16 in the liquidcrystal domain of the pixel region X of the other substrate vicinity 2a.

[0319] The orientation control layers 81 and 82, which are in contactwith the liquid crystal 6, are arranged on the sides of the substrates 1and 2 opposed to the liquid crystal layer 10. The orientation controllayers 81 and 82 control the angles θ1 and θ2 , which are formed by thecholesteric helical axes 61 and 62 of the liquid crystal 6 in the liquidcrystal domains of the pixel regions X in the substrate vicinities 1 aand 2 a with respect to the substrate normal H, respectively. Thecontrol by the orientation control layers 81 and 82 can increase ordecrease the angles θ1 and θ2. The angles vary in the following cases(c) and (d).

[0320] (c) The change or difference in angle is caused by the rubbing,which is effected on at least one of the orientation control layers 81and 82 arranged on the respective substrates 1 and 2. In this case, itis desirable that the orientation control layer thus rubbed has therubbing density of 10 or less. The angle may be increased or decreasedby partially effecting the rubbing on the orientation control layerthrough a mask having a predetermined pattern of openings. In any one ofthe above cases, the polydomain having helical axes of a smallerinclination than the original inclination can be obtained withoutcausing monodomain structure, depending on the material of theorientation film and/or rubbing conditions.

[0321] (d) The change or difference in angle is caused by theirradiation with predetermined light, which is effected on at least oneof the orientation control layers 81 and 82 arranged on the respectivesubstrates 1 and 2. In this case, increase or decrease in angles θ1 andθ2 may be controlled by the amount of the predetermined light emitted tothe orientation control layer, the substrate temperature during theirradiation of the orientation control layer with the predeterminedlight, the angle of the incident light on the substrate surface duringthe irradiation of the orientation control layer with the predeterminedlight, or the like. The light irradiation may be performed with a maskhaving a predetermined pattern of openings so that the orientationcontrol layer is partially irradiated with the light for changing theangle. In any one of the above cases, the polydomain having helical axesof a smaller inclination than the original inclination can be obtainedwithout causing monodomain structure, depending on the orientation filmmaterial and the light emitting conditions. In any one of the abovecases, the predetermined light may be ultraviolet light.

[0322] The material parameter may be different between -the orientationcontrol layers 81 and 82 arranged on the substrates 1 and 2. In thiscase, the orientation control layers 81 and 82, which are arranged onthe substrates 1 and 2 and have different material parameters, controlthe angles θ1 and θ2, which are formed by the cholesteric helical axes61 and 62 of the liquid crystal 6 in the liquid crystal domains of thepixel regions X in the substrate vicinities 1 a and 2 a with respect tothe substrate normal H, respectively. For providing different materialparameters, the orientation control layers 81 and 82 may be made ofdifferent kinds of materials, respectively. The material parameter maybe a pretilt angle, although not restricted thereto.

[0323] The difference between angles θ1 and θ2 may be caused by therubbing, which is effected on both the orientation control layers 81 and82 arranged on the substrates 1 and 2, respectively. The rubbingdensities of both the orientation control layers 81 and 82 thus rubbedare 10 or less.

[0324] In the liquid crystal light modulation element shown in FIG. 9,the angles θ1 and θ2 , which are formed by the cholesteric helical axes61 and 62 of the liquid crystal 6 in the liquid crystal domains of thepixel regions X in the substrate vicinities 1 a and 2 a in the selectivereflection state with respect to the substrate normal H, respectively,are 20° or less.

[0325] In the liquid crystal light modulation element shown in FIG. 9and other liquid crystal light modulation elements, the helical axes ofthe liquid crystal molecules in the focal conic state may be orientatedregularly in a plane substantially parallel to the substrate surface forthe purpose of reducing a light scattering effect in the focal conicstate.

[0326] In this case, orientation regulating means for the liquid crystalmolecules may be employed in the liquid crystal element for aligning ororientating helical axes of the liquid crystal molecules in the focalconic state in regular directions within a plane substantially parallelto a substrate surface.

[0327] The orientation regulating means for orientating helical axes inregular directions within a plane substantially parallel to a substratesurface may be means for controlling the electric field or means forcausing a difference in orientation regulating force.

[0328] (A) Means for controlling the electric field (a projectedstructure or a groove causing anisotropy in the directions of thepotential lines (in other words, the lines of electric force) ofelectric field) is as follows.

[0329]FIG. 12 shows projected structures 13 of a rib from, which are anexample of the orientation regulating means, and is formed in the liquidcrystal light modulation element shown in FIG. 9. FIG. 13 shows a stateof distortion caused in equal potential lines near the projectedstructure 13 in the liquid crystal light modulation element. FIG. 14shows a state, where electric field directions E are partially inclinedto specific directions. FIG. 12 does not show the resin structures 4which are practically formed. This is true also with respect to FIGS. 17and 19, which will be described later.

[0330] In FIG. 12, the projected structures 13 of the rib form arearranged on the substrate 2. The provision of the projected structure 13causes distortion in the equal potential lines 26 near the structurewhen a voltage is applied across the electrodes 11 and 12. Therefore,the electric field directions E (in other words, lines of electric forceof the electric field) are partially inclined to the specific directionsas shown in FIG. 14. When the application of the voltage is stopped inthe above state for changing the liquid crystal to the focal conicstate, the influence of the inclined electric field, which waspreviously present, restricts the direction of the helical axes of theliquid crystal. As a result, the helical axes 61 of the liquid crystalare regularly orientated in a plane substantially parallel to thesubstrate, as shown in FIGS. 15 and 16. Accordingly, it is possible toachieve the focal conic state, in which the helical axes 61 of theliquid crystal molecules are regularly orientated, and therefore thelight scattering is suppressed. FIG. 16 shows a state of the liquidcrystal light modulation element viewed from an upper side.

[0331] The projected structure is not restricted to the foregoingstructure 13, and may be selected from various forms.

[0332]FIG. 17 shows grooves (slits) 15, which are another example of theorientation regulating means, and are formed in the electrode 12 of theliquid crystal light modulation element shown in FIG. 9. FIG. 18 showsdistortion in the equal potential lines near the slit 12 formed in theelectrode 12 of the liquid crystal light modulation element.

[0333] As shown in FIG. 17, the slit 15 formed on the transparentelectrode 12 causes the distortion in the potential lines 26 near theslit 15 as shown in FIG. 18, and therefore it is possible for the samereason to achieve the focal conic state, in which the helical axes areregularly orientated, and the scattering is suppressed.

[0334] The groove may be formed in a portion other than the electrode,and may be formed in the insulating film or the like.

[0335] (B) Means for changing the orientation regulating force is asfollows.

[0336] A region providing a different orientation regulating force maybe used as another means for orientating the helical axes regularly inthe plane substantially parallel to the substrate. The region providingthe different orientation regulating force may be a region, which ananchoring force or an orientating force with respect to the liquidcrystal molecules is different. The region of the different orientationregulating force can be achieved by effecting rubbing processing oroptical orientation with ultraviolet light or the like on theorientation film (orientation control layer) of, e.g., polyimideuniformly coating the electrode surface. In particular, low-densityrubbing (e.g., of the rubbing density of 10 or less) maybe effect on thewhole orientation control layer, rubbing may be partially effected onthe orientation control layer through a mask having a predeterminedpattern of openings, or light irradiation may be partially effected onthe orientation control layer through a mask having a predeterminedpattern of openings, whereby the region providing the differentorientation regulating force can be formed. By forming the orientationfilm made of a partially different kind of material, the regionproviding the different orientation regulating force can be alsoachieved.

[0337] The region providing the different orientation regulating forcedoes not cause such a situation that the rubbing processing or the likecauses inclination in the electric field direction, but causes such asituation that the difference in surface regulating force determines thedirection of the helical axes during transition of the liquid crystalmolecules to the focal conic state, and thereby the effect can beachieved similarly the foregoing means of inclining the electric fielddirection.

[0338] In any one of the above cases, the above orientation processingcan bring about such an advantage that an addition member is notrequired in the liquid crystal display element for regularly orientatingthe helical axes in a plane parallel to the substrate, and therefore thereliability can be improved. In particular, the optical orientationprocessing is superior in view of the fact that the possibility ofcausing dust and others is low.

[0339] The manners of entirely or partially effecting the rubbing andthe manners of entirely or partially effecting the light irradiation maybe similar to the orientation controlling method employed in the fourthliquid crystal light modulation element, if it is provided with theorientation control layer, and the liquid crystal molecules in the mixedstate in the liquid crystal layer in the selective reflection state aresubjected to the orientation control by the orientation control layer(in the case of FIG. 11(A)). The manners of partially effecting therubbing, the manners of partially effecting the light irradiation andthe manner of employing a partially different material maybe similar tothe orientation control manner employed in the fifth liquid crystallight modulation element, if it is provided with the orientation controllayer, and the orientation control layer controls the angle of thecholesteric helical axis of the liquid crystal in each of the liquidcrystal domains of the pixel regions near the opposite substrates withrespect to the substrate normal when the liquid crystal layer is in theselective reflection state (in the case of FIG. 11(B)). By employing themanners similar to the foregoing orientation control manners, it ispossible to achieve the foregoing mixed state and the difference in theangle between the upper and lower substrates. At the same time, it ispossible to achieve the focal conic state causing less scattering.

[0340]FIG. 19 shows an example of the region 16, which is partiallyprocessed in the above manner, and is arranged on the orientationcontrol layer (orientation film) 82 in the liquid crystal lightmodulation element shown in FIG. 9.

[0341] The orientation control layer, which is provided with thepartially processed region, may be configured to perform the orientationcontrol of the liquid crystal molecules for obtaining the mixed state ofthe liquid crystal layer in the selective reflection state, as is donein the case of FIG. 11(A). Also, as is done in the case of FIG. 11(B),it may be configured to control the angle with respect to the substratenormal of the cholesteric helical axis of the liquid crystal in each ofthe liquid crystal domains of the pixel regions near the oppositesubstrate vicinities of the liquid crystal layer in the selectivereflection state. In any one of the above cases, it is possible toorientate regularly the helical axes of the liquid crystal in the focalconic state in a plane substantially parallel to the substrate.

[0342] As the manner of controlling the angle with respect to thesubstrate normal of the cholesteric helical axis of the liquid crystalin each of the liquid crystal domains of the pixel regions near theopposite substrate vicinities in the selective reflection state, such amanner can be effectively employed as appropriately selecting the kindof material of the substrate surface, which may be formed of e.g., filmon the substrate, nearest to the cholesteric liquid crystal and/orappropriately processing the substrate surface in accordance with thekind of the cholesteric liquid crystal material.

[0343] If the substrate surface nearest to the cholesteric liquidcrystal is formed of a film, the material of such surface may be thesame as the foregoing electrode and insulating film as well aspolyimide. The polyimide is most preferable in view of the fact that theinteraction with respect to the cholesteric liquid crystal can be easilychanged by the orientation processing, which will be described later.The thickness of the film is merely required to be of a value, whichallows application of the voltage to the cholesteric liquid crystal, anddoes not remarkably reduce the light transmittance.

[0344] The manner of performing the orientation processing may be therubbing processing, in which the surface to be processed is rubbed in auniform direction, e.g., with a cloth or the like. In the case where thesubstrate surface nearest to the cholesteric liquid crystal is formed ofthe film (e.g., polyimide film), such a manner can be appropriatelyemployed that the formed film is irradiated with non-polarized light orlinear-polarized light (e.g., ultraviolet light) for causingisomerization, dimerization, decomposition or the like for causing theanisotropy.

[0345] If the rubbing processing is employed, such a rubbing device maybe employed that is provided with a rubbing roller having a rubbingcloth of a predetermined fiber or brush height. The substrate is movedin a predetermined direction at a predetermined moving speed, and therubbing roller rotating in a predetermined direction at a predeterminedrotation speed is brought into contact with the nearest substratesurface so that the nearest substrate surface is rubbed. If this rubbingdevice provided with the rubbing roller is employed, the orientationcontrol of the liquid crystal molecules can be performed depending onthe pressed fiber or brush height of the rubbing cloth, times ofrubbing, rubbing roller radius, rubbing roller rotation speed and thesubstrate moving speed.

[0346] Assuming that N indicates the rubbing times, r indicates therubbing roller radius, m indicates the rubbing roller rotation speed andv indicates the substrate moving speed, the rubbing density L expressedby the following formula (1) is an important parameter.

L=N{1+2πrm/v}  (formula 1)

[0347] If the rubbing density is equal to about 100, the helical axes ofthe cholesteric liquid crystal are perfectly or substantially perfectlyperpendicular to the substrate surface so that the foregoing bistabilityeffect is liable to be lost. If the rubbing density is smaller than 100,it is considered that the substrate surface is not entirely rubbed, andthe rubbing effect is partially achieved. Thereby, some helical axes ofthe liquid crystal are perfectly or substantially perfectlyperpendicular to the substrate surface, and the others have inclinationwith respect to the substrate normal. In a range (e.g., having a side ofabout 100 μm) corresponding one pixel of the liquid crystal lightmodulation element, the inclination of the helical axes of the liquidcrystal serves as an average in this range, and provides a certain anglewith respect to the substrate normal. A similar effect can be achievedeven in the case where the rubbing density of the rubbing-target regioncorresponding to the opening portion of the mask layer is increased bythe partial rubbing method, in which the rubbing processing is partiallyperformed, e.g., with the mask layer.

[0348] When the optical orientation processing is employed by, e.g.,irradiating the processing-target region with ultraviolet light, theorientation control for the liquid crystal molecules can be achieveddepending on the illuminance of ultraviolet light, light irradiationperiod, substrate temperature during the light irradiation, incidentlight angle on the substrate surface, or the like.

[0349] Similarly to the partial orientating method (partial rubbingmethod) already described, the partial optical orientation processingfor performing the exposure with a photomask can be effectively used.

[0350] A similar effect can be achieved also in the case where thenearest surface films of the opposite substrates are made of differentmaterials (e.g., polyimide film materials), respectively. Morespecifically, a similar effect can be achieved in the case where thesurface films of the opposite substrates are made of materials providingthe different pretilt angles determined by the rubbing, respectively, orthe materials providing the same pretilt angle but having differentmaterial compositions, respectively.

[0351] In an example of the method of partially effecting the rubbingprocessing on the orientation control film (orientation film), aphotoresist material is applied, e.g., by spin coating to theorientation film, and then is removed from the portion to be rubbed byconventional photolithography, and then the rubbing is performed.Thereafter the resist is removed. Thereby, the rubbed region isprepared. The rubbing direction is not restricted.

[0352] The method of partially performing the optical orientationprocessing may be performed by effecting the ultraviolet light exposure,e.g., through a photomask and a polarizing plate. This can easilyprovide the optically orientated region.

[0353] FIGS. 20(A)-20(D) show an example of steps for partiallyprocessing the orientation film in the foregoing method. This exampleincludes the following steps.

[0354] In FIG. 20(A), the insulating film 7 is formed on the electrodesurface of the substrate 2 provided with the patterned electrodes 12.

[0355] In FIG. 20(B), the orientation film 82 is formed on theinsulating film 7.

[0356] In FIG. 20(C), the orientation film 82 is exposed to the lightcoming from a light source 70 through an opening portions 73 in a mask72, or In FIG. 20(C′), a resist film 40 is formed on the orientationfilm 82, and is patterned.

[0357] Then, rubbing processing 64 is effected on the orientation film82 through opening portions 41 in the resist film 40. Then, the resistfilm 40 is removed.

[0358] In FIG. 20(D), through the above, the partially processed regions16 are formed.

[0359] Through the above steps, the regions 16 having a desired form canbe formed in intended positios by a relatively simple manner.

[0360] The method of using the different kinds of orientation films canbe performed in such a manner that, after patterning the resist film inthe step shown in FIG. 20(C′), different kinds of orientation films areapplied and baked, and the resist film is removed.

[0361] The liquid crystal light modulation element shown in FIG. 9 canemploy the regions 16 thus obtained in the orientation control layer 82in the case shown in FIG. 11(A), or in each of the orientation controllayers 81 and 82 in the case shown in FIG. 11(B).

[0362] As described above, the surface treatment is effected on thesubstrate, or the material of the substrate surface nearest to theliquid crystal is selected so that the difference is caused in theinclination (angle with respect to the substrate normal) of the helicalaxis of the cholesteric liquid crystal between the opposite substrates.In this case, the cholesteric domains near the respective substrateshave different structures, and provide different optical reflectioncharacteristics in the planar state.

[0363] In the liquid crystal light modulation element, which performsthe display by the selective reflection of the visible light by thecholesteric liquid crystal, if the inclination (angle with respect tothe substrate normal) of the helical axis of the liquid crystal isrelatively large, the spectrum half bandwidth is large, and thus goodview angle characteristics can be achieved, although the lightreflectance is low at the front on the element observation side. On theother hand, if the inclination (angle with respect to the substratenormal) of the helical axis of the liquid crystal is relatively small,the light reflectance and color purity are high at the front on theelement observation side, and the view angle characteristics arerelatively low. Accordingly, as compared with the non-orientatedcholesteric liquid crystal display element, good brightness and goodcolor purity characteristics can be achieved at the front on the elementobservation side while maintaining the bistability. If the inclination(angle with respect to the substrate normal) of the helical axis of theliquid crystal on the element observation side is larger than that onthe non-observation side (opposite side), the light reflected by thecholesteric domain having the helical axes of small inclination isslightly scattered by the cholesteric domain having the helical axes oflarge inclination. This is advantageous from the viewpoint of the viewangle characteristics.

[0364] The following formula (2) expresses a wavelength λ of theselectively reflected light derived from the incident light which isinclined with respect to the helical axis direction in the planarorientation of the cholesteric liquid crystal. $\begin{matrix}{\lambda = {\overset{\_}{n}p\quad \cos \quad {\frac{1}{2}\left\lbrack {{\sin^{- 1}\left( {\frac{1}{n}\sin \quad \varphi_{i}} \right)} + {\sin^{- 1}\left( {\frac{1}{n}\sin \quad \varphi_{s}} \right)}} \right\rbrack}}} & \text{(formula~~2)}\end{matrix}$

[0365] wherein n represents an average refractive index, p represents ahelical pitch of the cholesteric liquid crystal, n represents an averagerefractive index of the liquid crystal, φi and φs represent incident andreflection angles of the light with respect to the helical axis,respectively.

[0366] Accordingly, the inclination (angle with respect to the substratenormal) of the helical axis of the liquid crystal can be easilycalculated by preparing a liquid crystal cell exhibiting equal orsimilar inclination angles of the helical axes of the liquid crystals inthe opposite substrates, measuring the spectral transmittance of theliquid crystal cell and comparing the spectral transmittance and theselective reflection wavelengths of the cholesteric cells having rubbedopposite substrate surfaces.

[0367] The cell subjected to the high-density rubbing exhibits thehelical axis angle of 0°. With respect to this cell, the celltransmittance is measured, and the selective reflection centerwavelength is read out from the obtained spectrum.

[0368] Assuming that the wavelength is λ0, the following relationship isobtained: $\begin{matrix}{\lambda_{0} = {\overset{\_}{n}p\quad \cos \quad {\frac{1}{2}\left\lbrack {{\sin^{- 1}\left( {\frac{1}{n}\sin \quad 0} \right)} + {\sin^{- 1}\left( {\frac{1}{n}\sin \quad 0} \right)}} \right\rbrack}}} & \text{(formula~~3)}\end{matrix}$

[0369] Accordingly, np is obtained.

[0370] Then, measurement is made on a cell having a helical axis angleof few degrees, and the central wavelength is likewise read out.

[0371] Assuming that the wavelength is λ′, the following relationship isobtained: $\begin{matrix}{\lambda^{\prime} = {\overset{\_}{n}p\quad \cos \quad {\frac{1}{2}\left\lbrack {{\sin^{- 1}\left( {\frac{1}{n}\sin \quad \varphi_{s}} \right)} + {\sin^{- 1}\left( {\frac{1}{n}\sin \quad \varphi_{s}} \right)}} \right\rbrack}}} & \text{(formula~~4)}\end{matrix}$

[0372] By substituting the result of the formula (3) into the formula(4), the angle λs is obtained. The angle λs is the inclination angle ofthe helical axis.

[0373] By the above manners, the inclination (angle to the substratenormal) of the helical axis of the liquid crystal was calculated, andthe display characteristics were compared. According to the result, theliquid crystal light modulation element having the helical axisinclination of 20° or less is superior in view of the brightness and thecolor purity. In contrast to this, the liquid crystal light modulationelement having the helical axis inclination larger than 20° is inferiorin view of the color purity because the scattering between the domainsis large. The multilayer liquid crystal light modulation element formedof such elements has a low light transmittance. Accordingly, it isdesired that the helical axis inclination of the liquid crystal is 20°or less.

[0374] The liquid crystal light modulation element may be provided withspacers, which are arranged between the paired substrates, and serves asa spacer member for defining a gap and keeping a uniform gap between thesubstrates. The spacer member defining the gap may be spherical spacerparticles of, e.g., glass or plastics. In addition to the above, it maybe provided with a thermoplastic or thermosetting columnar adhesive. Theliquid crystal light modulation element shown in FIG. 9 includes thespacers 5 arranged between the substrates 1 and 2, already described.

[0375] The liquid crystal light modulation element shown in FIG. 9 andother liquid crystal light modulation elements may be provided with astructure serving as a space keeping member and carrying the pairedsubstrates for providing a strong self-holding property. The liquidcrystal light modulation element in FIG. 9 is provided with the resinstructures 4 located between the substrates 1 and 2. The resinstructures 4 are equally spaced and arranged in accordance with apredetermined arrangement rule (e.g., grid arrangement), and each mayhave a columnar dot-like form having a circular, square or ellipticsection.

[0376] For holding the liquid crystal material between the pairedsubstrates, a known vacuum-supply method or a liquid crystal droppingmethod may be appropriately used depending on the intended size of theliquid crystal cell and cell gap. These liquid crystal material holdingmethods cause no difference in effect exerted on the direction of thehelical axis of the liquid crystal with respect to the substrate normal.

[0377] The seal member may be thermosetting or photo-setting adhesivesuch as epoxy resin or acrylic resin.

[0378] For driving the liquid crystal light modulation element, it isdesired to use a combination of high and low voltages of each having asquare waveform. In this case, the planar state of the cholestericliquid crystal can be achieved by suddenly turning off the voltage inthe homeotropic state where all the liquid crystal molecules areorientated in the electric field direction. The focal conic state can beobtained by applying a low voltage pulse to the planar state, orapplying a low voltage pulse immediately after the homeotropic state.

[0379] A plurality of cholesteric liquid crystal light modulationelements each having the above structures and the above characteristicsbut having different selective reflection wavelengths may be stacked toprovide the multicolor display element of the reflection type. Inparticular, the selective reflection wavelengths for the red (R), green(G) and blue (B) may be employed, whereby the full-color display can beachieved.

[0380]FIG. 21 is a schematic cross section of a multilayer liquidcrystal light modulation element, in which liquid crystal lightmodulation elements for display in blue, green and red are stacked orlayered in this order. In the respective liquid crystal light modulationelements of the multilayer liquid crystal light modulation element shownin FIG. 21 is the substantially same as that shown in FIG. 9, andportions having the substantially same structures and the substantiallysame functions bear the same reference numbers, respectively.

[0381] In each of the liquid crystal light modulation elements B, G andR in the multilayer element shown in FIG. 21, a liquid crystal layer 10b, 10 g or 10 r for display in blue, green or red is held between thepaired substrates 1 and 2. The liquid crystal layers 10 b, 10 g and 10 rcontain liquid crystal materials 6 b, 6 g and 6 r exhibiting acholesteric phase at a room temperature and having the peaks of theselective reflection wavelengths in the visible wavelength range,respectively.

[0382] A visible light absorber layer is arranged on the outer surface(rear surface) of the substrate remote from the element observation sideP (light incident side), if necessary. In the example shown in FIG. 21,the visible light absorber layer 3 is arranged on the outer surface(rear surface) of the substrate 2 in the liquid crystal light modulationelement R.

[0383] In the multilayer liquid crystal light modulation element shownin FIG. 21, a predetermined voltage is applied to switch the liquidcrystal 6 b, 6 g and 6 r between the planar state (selective reflectionstate) and the focal conic state.

[0384] In the liquid crystal light modulation element shown in FIG. 21and other liquid crystal light modulation elements, the neighboringliquid crystal layers may employ a common substrate between them.

[0385]FIG. 22 shows common substrates each forming the substrate 1 (and2) located between neighboring liquid crystal light modulation elementsB and G, or between G and R in the multilayer liquid crystal lightmodulation element in FIG. 21.

[0386] In the multilayer liquid crystal light modulation element, it isimportant for achieving high color purity to reduce the scatteringcomponents of the light passing through each cell (liquid crystal lightmodulation element) in an appropriate manner. As described above, thelight transmittance of the cell can be improved by reducing theinclination (angle with respect to the substrate normal) of the helicalaxis of the liquid crystal. However, excessively small inclination ofthe helical axis lowers the view angle characteristics, as alreadydescribed. Therefore, such a structure is employed that the inclinationof the helical axis is relatively small on one side, and the inclinationof the helical axis is relatively large on the other side. Thereby, theliquid crystal light modulation element of the reflection type canachieve appropriate brightness, contrast and color purity.

[0387] In the multilayer liquid crystal light modulation element, theinclination (angle with respect to the substrate normal) of the helicalaxis of the liquid crystal is controlled in each liquid crystal lightmodulation element layer. Thereby, characteristics having furtherimproved viewability can be achieved. Thus, the cholesteric liquidcrystal domain can scatter the light to a certain extent when it is inthe planar state. Therefore, the helical axis inclination of the liquidcrystal in the liquid crystal light modulation element layer remote fromthe element observation side is relatively reduced, and the scatteringeffect of the liquid crystal light modulation element on the upper layeris used to scatter the light, whereby both the high color purity and thehigh light reflectance can be achieved.

[0388] Accordingly, in the structure including the blue, green and redliquid crystal light modulation elements, which are stacked in thisorder from the element observation side, the blue liquid crystal elementhaving the largest helical axis inclination of the liquid crystal, andthe red liquid crystal element has the smallest helical axis inclinationof the liquid crystal. For example, the following relationships aredesirable for improving the viewability of the liquid crystal lightmodulation elements. In any neighboring liquid crystal opticalmodulation elements, the inclination (angle with respect to thesubstrate normal) of the cholesteric helical axis of the liquid crystalin the liquid crystal domain of the pixel region near the substrate onthe element observation side in the liquid crystal light modulationelement on the element observation side is larger than the inclination(angle with respect to the substrate normal) of the cholesteric helicalaxis of the liquid crystal in the liquid crystal domain of the pixelregion near the substrate on the element observation side in the liquidcrystal light modulation element on the side remote from the elementobservation side. Also, the inclination (angle with respect to thesubstrate normal) of the cholesteric helical axis of the liquid crystalin the liquid crystal domain of the pixel region near the substrateremote from the element observation side in the liquid crystal lightmodulation element on the element observation side is larger than theinclination (angle with respect to the substrate normal) of thecholesteric helical axis of the liquid crystal in the liquid crystaldomain of the pixel region near the substrate on the side remote fromthe element observation side in the liquid crystal light modulationelement on the side remote from the element observation side.

[0389] Between the neighboring liquid crystal light modulation elements,a difference may be caused in the helical axis inclination for furtherimproving the above effect. For example, in any neighboring liquidcrystal optical modulation elements, the inclination (inclination withrespect to the substrate normal) of the cholesteric helical axis of theliquid crystal in the liquid crystal domain of the pixel region near thesubstrate on the element observation side in the liquid crystal lightmodulation element on the element observation side may be different fromthe inclination (inclination with respect to the substrate normal) ofthe cholesteric helical axis of the liquid crystal in the liquid crystaldomain of the pixel region near the substrate on the element observationside in the liquid crystal light modulation element on the side remotefrom the element observation side. Also, the inclination (inclinationwith respect to the substrate normal) of the cholesteric helical axis ofthe liquid crystal in the liquid crystal domain of the pixel region nearthe substrate remote from the element observation side in the liquidcrystal light modulation element on the element observation side may bedifferent from the inclination (inclination with respect to thesubstrate normal) of the cholesteric helical axis of the liquid crystalin the liquid crystal domain of the pixel region near the substrate onthe side remote from the element observation side in the liquid crystallight modulation element on the side remote from the element observationside.

[0390] In the multilayer liquid crystal light modulation elements shownin FIGS. 21 and 22, the neighboring liquid crystal light modulationelements B and G (G and R) are in such a relationship that the anglewith respect to the substrate normal of the cholesteric helical axis ofthe liquid crystal 6 b (6 g) in the liquid crystal domain of the pixelregion X in the substrate vicinity la (see FIGS. 11(A) and 11(B))on theelement observation side P in the liquid crystal light modulationelement B (G) on the element observation side P is larger than the anglewith respect to the substrate normal of the cholesteric helical axis ofthe liquid crystal 6 g (6 r) in the liquid crystal domain of the pixelregion X in the substrate vicinity la on the element observation side Pin the liquid crystal light modulation element G (R) on the side remotefrom the element observation side P, and the angle with respect to thesubstrate normal of the cholesteric helical axis of the liquid crystal 6b (6 g) in the liquid crystal domain of the pixel region X in thesubstrate vicinity 2 a (see FIGS. 11(A) and 11(B)) on the side remotefrom the element observation side P in the liquid crystal lightmodulation element B (G) on the element observation side P is largerthan the angle with respect to the substrate normal of the cholesterichelical axis of the liquid crystal 6 g (6 r) in the liquid crystaldomain of the pixel region X in the substrate vicinity 2 a on the sideremote from the element observation side P in the liquid crystal lightmodulation element G (R) on the side remote from the element observationside P.

[0391] The neighboring liquid crystal light modulation elements B and G(G and R) are in such a relationship that the rubbing density of therubbed orientation control layer in the liquid crystal light modulationelement B (G) on the element observation side P is smaller than that ofthe orientation control layer, corresponding to the above control layer,in the liquid crystal light modulation element G (R) on the side remotefrom the element observation side P.

[0392] In the liquid crystal light modulation element (multilayer liquidcrystal light modulation element) described above, the state (1) alreadydescribed may be attained in each liquid crystal domain at the pixelregion X of each of the substrate vicinities 1 a and 2 a opposed to theopposite substrates 1 and 2 in the liquid crystal layer 10 (10 b, 10 gor 10 r) in the selective reflection state. In this case (1), the mixedstate of the polydomain(s) and monodomain(s) is attained in the liquidcrystal domain at the pixel region X of at least one (2 a) of thesubstrate vicinities 1 a and 2 a opposed to the opposite substrates 1and 2 in the liquid crystal layer 10 (10 b, 10 g or 10 r) in theselective reflection state. Also, in the case (2) already described,each liquid crystal domain at the pixel region X of the oppositesubstrate vicinities 1 a and 2 a opposed to the opposite substrates 1and 2 has the polydomain structure, and the cholesteric helical axes 61and 62 of the liquid crystal in the liquid crystal domains at the pixelregions X in the substrate vicinities 1 a and 2 a define differentangles θ1 and θ2 with respect to the substrate normal H, respectively.Therefore, good images with high brightness, contrast and color puritycan be displayed. Further, the displayed state with high brightness,contrast and color purity can be maintained for a long term when avoltage is not applied. In other words, the characteristics achievingthe high reflection intensity, high contrast and high color purity inthe planar state can be achieved together with the bistability.

[0393] The region providing a different orientation regulating force isformed in the orientation film (orientation control layer) for regularlyorientating the helical axes of the liquid crystal molecules in thefocal conic state in a plane substantially parallel to the substratesurface. Therefore, the light transmittance of the liquid crystal layerin the focal conic state is improved, and the contrast can be improved.

[0394] Description will now be given on experiments, which wereperformed for evaluating the performances of the liquid crystal opticalmodulation elements, together with comparative examples. Naturally, theinvention is not restricted to these experimental examples.

[0395] In the respective experimental examples and comparativeexperimental examples, liquid crystal elements having the substrate,which are processed under different conditions (material of orientationcontrol films, rubbing processing, optical orientation processing andothers) were produced, and evaluation was made on the visibility(reflectance and color purity on the element observation side) at thefront of the element observation side, memory characteristics(bistability) and view angle characteristics (reflectances atpredetermined observation angles).

[0396] In each of the respective experimental examples and comparativeexamples, the measurement of the inclination (angle with respect to thesubstrate surface) of the helical axis of the liquid crystal in theliquid crystal light modulation element was performed in such a mannerthat cell having opposite substrates provided with orientation controlfilms of the same structure was employed, the cell filled with theliquid crystal was set to the planar state by applying a predeterminedhigh voltage pulse to the cell, and the light transmittance of the cellin the planar state was measured. In this measurement, the selectivereflection peak wavelength was read out, the average inclination of thehelical axis of the liquid crystal was calculated from the foregoingformula (2).

Experimental Conditions

[0397] Each liquid crystal layer of the single layer cell was 5 μm inthickness.

[0398] Driving was performed by pulse voltage driving using thefollowing pulse.

[0399] A planar state was selected with a pulse of 3 ms and 80 V−60 V.

[0400] A focal conic state was selected with a pulse of 3 ms and 40 V.

[0401] Evaluation of the stability of the memory characteristics wasperformed by making a comparison between a reflection characteristicvalue (Y value) determined immediately after application of the pulsevoltage and a reflection characteristic value (Y value-) determinedafter leaving the cell for one month.

[0402] Evaluation of the view angle characteristics was performed bymeasuring the peak reflectance while emitting the light at an angle of30° with respect to the normal line on the element observation side andchanging the detection angle with respect to the normal line on theelement observation side.

[0403] The rubbing processing was performed by the rubbing device, whichwas provided with a rubbing roller having a rubbing cloth of apredetermined brush height. The substrate was moved at a predeterminedspeed in a predetermined direction, and the rubbing roller rotating in apredetermined direction at a predetermined rotation speed was broughtinto contact with the substrate uppermost surface so that the substratesurface was rubbed.

[0404] The rubbing density was determined in accordance with theforegoing formula (1).

[0405] In each of the experimental examples and comparative examples,the light reflectance, color purity and reflection characteristics value(Y-value) were measured with a reflective spectrocolorimeter CM-3700d(manufactured by Minolta Co., Ltd.).

Experimental Example 1

[0406] In this experiment, the liquid crystal display element wasemployed, in which the inclination (angle of the helical axis of theliquid crystal in the selective reflection state with respect to thesubstrate normal) of the helical axis of the liquid crystal wasdifferent between the upper and lower substrates (i.e., the upper andlower substrates were provided with orientation control films ofdifferent materials, respectively).

[0407] <Orientation Control Film on the Observation Side>

[0408] Orientation control film material:

[0409] polyimide

[0410] JALS-1024-R (manufacture by JSR Corp.)

[0411] non-rubbing

[0412] Inclination of helical axis (average):

[0413] about 18°

[0414] Deposition conditions:

[0415] flexo print of orientation control film material

[0416] preliminary baking with 80° C. for 2 minutes

[0417] baking with 140° C. for 60 minutes

[0418] Thickness of orientation control film 500 Å

[0419] <Orientation Control Film on the Non-Observation Side Opposite tothe Observation Side>

[0420] Orientation control film material:

[0421] polyimide

[0422] AL1454 (manufacture by JSR Corp.)

[0423] non-rubbing

[0424] Inclination of helical axis (average):

[0425] about 7°

[0426] Deposition conditions:

[0427] flexo print of orientation control film material preliminarybaking with 80° C. for 2 minutes

[0428] baking with 140° C. for 60 minutes

[0429] Thickness of orientation control film 500 Å

[0430] <Liquid Crystal>

[0431] Liquid crystal material:

[0432] nematic liquid crystal E31-LV manufactured by Merk & Co. andchiral agent S-811 (24.5 wt %) manufactured by Merk & Co.

[0433] Selective reflection peak wavelength: λ=550 nm

[0434] By observation with a polarization microscope, it was confirmedthat all the liquid crystal near the orientation control films on thesubstrates took polydomain state in the planar state.

[0435] In this experiment, the liquid crystal display element providedthe reflectance of 35% and the color purity of 75% on the elementobservation side, and exhibited high visibility at the front on theelement observation side.

[0436] The view angle characteristics of this liquid crystal displayelement are shown in FIG. 23. As shown in FIG. 23, the reflectance atthe observation angle of 30° was 50% or more of the reflectance at theobservation angle of 0° so that it can be considered that the view anglecharacteristics were in a sufficiently practicable range.

[0437] When the focal conic state was attained by application of thepulse voltage, the Y-value of 1.2 was obtained immediately after thevoltage application, and the Y-value of 1.3 was obtained after onemonth. Thus, the liquid crystal display element of this experiment couldsuppress the change in display characteristics, and had the good memorycharacteristics.

Experimental Example 2

[0438] This experiment was performed with another example of the liquidcrystal display element of a single layer, in which the inclination(angle of the helical axis of the liquid crystal in the selectivereflection state with respect to the substrate normal) of the helicalaxis of the liquid crystal was different between the upper and lowersubstrates (i.e., the rubbing was effected on the orientation controlfilm of only one of the substrates).

[0439] <Orientation Control Film on the Observation Side>

[0440] Orientation control film material:

[0441] polyimide

[0442] JALS-1024-R (manufacture by JSR Corp.)

[0443] non-rubbing

[0444] Inclination of helical axis (average):

[0445] about 18°

[0446] Deposition conditions:

[0447] flexo print of orientation control film material

[0448] preliminary baking with 80° C. for 2 minutes

[0449] baking with 140° C. for 60 minutes

[0450] Thickness of orientation control film 500 Å

[0451] <Orientation Control Film on the Non-Observation Side>

[0452] Orientation control film material:

[0453] polyimide

[0454] JALS-1024-R (manufacture by JSR Corp.)

[0455] Rubbing was effect on the entire area.

[0456] Inclination of helical axis (average):

[0457] about 4°

[0458] Deposition conditions:

[0459] flexo print of orientation control film material

[0460] preliminary baking with 80° C. for 2 minutes

[0461] baking with 140° C. for 60 minutes

[0462] Thickness of orientation control film 500 Å

[0463] Rubbing conditions

[0464] pressed brush height(pressed amount): 0.4 mm

[0465] roller radius: 75 mm

[0466] roller rotation speed: 0

[0467] substrate moving speed: 30 mm/sec

[0468] rubbing times: 5

[0469] rubbing density: 5

[0470] <Liquid Crystal>

[0471] Liquid crystal material:

[0472] nematic liquid crystal E31-LV manufactured by Merk & Co. andchiral agent S-811 (24.5 wt %) manufactured by Merk & Co.

[0473] Selective reflection peak wavelength: λ=550 nm

[0474] By observation with a polarization microscope, it was confirmedthat all the liquid crystal near the orientation control film on theobservation side was in the polydomain state in the planar state, andthe liquid crystal near the orientation control film on thenon-observation side was in the mixed state of the polydomain state andmonodomain state.

[0475] In this experiment, the liquid crystal display element providedthe reflectance of 40% and the color purity of 78% on the elementobservation side, and exhibited high visibility at the front on theelement observation side.

[0476] The view angle characteristics of this liquid crystal displayelement are plotted with “◯” in FIG. 24. As shown in FIG. 24, thereflectance at the observation angle of 30° was 50% or more of thereflectance at the observation angle of 0° so that it can be consideredthat the view angle characteristics were in a sufficiently practicablerange.

[0477] When the focal conic state was attained by application of thepulse voltage, the Y-value of 1.3 was obtained immediately after thevoltage application, and the Y-value of 1.5 was obtained after onemonth. Thus, the liquid crystal display element of this experiment couldsuppress the change in display characteristics, and had the good memorycharacteristics.

Comparative Experimental Example 1

[0478] This experiment differed from the experimental example 2 in thatthe rubbing density of the polyimide film on the non-observation sidewas increased so that the liquid crystal near this polyimide filmentirely took the monodomain state when it was in the planar state.Also, the following conditions were different from those in theexperimental example 2.

[0479] Other than the above is the same as the example 2.

[0480] Rubbing Conditions

[0481] roll rotation speed: 550 rpm

[0482] rubbing times: 2

[0483] rubbing density: about 290

[0484] inclination of helical axis: about 0° on average

[0485] By observation with a polarization microscope, it was confirmedthat the liquid crystal near the orientation control film on thenon-observation side took substantially entirely monodomain state in theplanar state.

[0486] The view angle characteristics of this liquid crystal displayelement are plotted with solid circles in FIG. 24. As shown by solidcircles in FIG. 24, the reflectance at the front was high, but the viewangle characteristics were inferior to that of the liquid crystalelement of the experimental example 2. It can also be seen that thereflectance with the observation angle of 30° decreased to about 10% ofthe reflectance with the observation angle of 0°.

[0487] When the focal conic state was attained by application of thepulse voltage, the Y-value was equal to 1.4 immediately after thevoltage application, and was 6.7 after one month. Thus, the memorycharacteristics were deteriorated in the liquid crystal element of thisexperiment.

Comparative Example 2

[0488] This experiment differed from the experiment 2 in that each ofthe upper and lower substrates of the liquid crystal element was notsubjected to the rubbing.

[0489]FIG. 25 shows view angle characteristics of this liquid crystalelement. As shown in FIG. 25, the view angle characteristics weresufficiently allowable, but the reflectance at the front of the elementobservation side was smaller by about 38% than that of the experimentalexample 2.

[0490] The Y-value was equal to 1.2 immediately after the voltageapplication and after one month, and no change occurred in the memorycharacteristics.

Experimental Example 3

[0491] This experiment differs from the experimental example 2 in thatthe liquid crystal element was provided with the polyimide film having arelatively large rubbing density (equal to 10) on the non-observationside. The average inclination of the helical axis was about 4°.

[0492] By observation with a polarization microscope, it was confirmedthat the liquid crystal near the orientation control film on thenon-observation side was in the mixed state of the polydomain state andmonodomain state in the planar state.

[0493] The view angle characteristics of this liquid crystal elementwere plotted with “◯” in FIG. 26. In FIG. 26, solid circles “”represent the result of the experimental example 2. As can be seen fromFIG. 26, the view angle characteristics similar to those of theexperimental example 2 were obtained. Results similar to those of theexperimental example 2 were also obtained with respect to thereflectance at the front, color purity, memory characteristics for along term.

Experimental Example 4

[0494] This experiment was performed with further another example of theliquid crystal display element of a single layer, in which theinclination (angle of the helical axis of the liquid crystal in theselective reflection state with respect to the substrate normal) of thehelical axis of the liquid crystal was different between the upper andlower substrates (i.e., the optical orientation processing is effectedon the orientation control film of only one of the substrates).

[0495] <Orientation Control Film on the Observation Side>

[0496] Orientation control film material:

[0497] polyimide

[0498] TT-054 (Hitachi Chemical Co., Ltd.)

[0499] non-rubbing

[0500] Inclination of helical axis (average):

[0501] about 16°

[0502] Deposition conditions:

[0503] flexo print of orientation control film material

[0504] preliminary baking with 100° C. for 1 minutes

[0505] baking with 230° C. for 30 minutes

[0506] Thickness of orientation control film 500 Å

[0507] <Orientation Control Film on the Non-Observation Side>

[0508] Orientation control film material:

[0509] polyimide

[0510] TT-054 (Hitachi Chemical Co., Ltd.)

[0511] Optical orientation was effected.

[0512] Inclination of helical axis (average):

[0513] about 6°

[0514] Deposition conditions:

[0515] flexo print of orientation control film material

[0516] preliminary baking with 100° C. for 1 minutes

[0517] baking with 230° C. for 30 minutes

[0518] Thickness of orientation control film 500 Å

[0519] UV irradiation conditions

[0520] 5 J/cm²

[0521] incident angle 15°

[0522] substrate temperature 23° C.

[0523] The whole substrate surface was irradiated through a polarizingplate.

[0524] <Liquid Crystal>

[0525] Liquid crystal material:

[0526] nematic liquid crystal E31-LV manufactured by Merk & Co. andchiral agent S-811 (24.5 wt %) manufactured by Merk & Co.

[0527] Selective reflection peak wavelength: λ=550 nm

[0528] By observation with a polarization microscope, it was confirmedthat the liquid crystal near the orientation control film on theobservation side took entirely polydomain state in the planar state, andthe liquid crystal near the orientation control film on thenon-observation side was in the mixed state of the polydomain state andmonodomain state.

[0529] In this experiment, the liquid crystal display element providedthe reflectance of 38% and the color purity of 72% on the elementobservation side, and exhibited high visibility at the front on theelement observation side.

[0530] Although the view angle characteristics of this liquid crystaldisplay element are not shown in the figure, the reflectance at theobservation angle of 30° was 20%, and was 50% or more of the reflectanceat the observation angle of 0° so that it can be considered that theview angle characteristics were in a sufficiently practicable range.

[0531] When the focal conic state was attained by application of thepulse voltage, the Y-value of 1.3 was obtained immediately after thevoltage application, and the Y-value of 1.4 was obtained after onemonth. Thus, the liquid crystal display element of this experiment couldsuppress the change in display characteristics, and had the good memorycharacteristics.

Experimental Example 5

[0532] This experiment was performed with further another example of theliquid crystal display element of a single layer, in which theinclination (angle of the helical axis of the liquid crystal in theselective reflection state with respect to the substrate normal) of thehelical axis of the liquid crystal was different between the upper andlower substrates (i.e., the optical orientation processing was effectedon the orientation control films of the opposite substrates withdifferent amounts of exposure light, respectively).

[0533] <Orientation Control Film on the Observation Side>

[0534] Orientation control film material:

[0535] polyimide

[0536] TT-054 (Hitachi Chemical Co., Ltd.)

[0537] Optical orientation was effected.

[0538] Inclination of helical axis (average):

[0539] about 12°

[0540] Deposition conditions:

[0541] flexo print of orientation control film material

[0542] preliminary baking with 100° C. for 1 minutes

[0543] baking with 230° C. for 30 minutes

[0544] Thickness of orientation control film 500 Å

[0545] Irradiation conditions

[0546] 2 J/cm²

[0547] incident angle 15°

[0548] substrate temperature 23° C.

[0549] The whole substrate surface was irradiated through a polarizingplate.

[0550] <Orientation Control Film on the Non-Observation Side>

[0551] Orientation control film material:

[0552] polyimide

[0553] TT-054 (Hitachi Chemical Co., Ltd.)

[0554] Optical orientation was effected.

[0555] Inclination of helical axis (average):

[0556] about 6°

[0557] Deposition conditions:

[0558] flexo print of orientation control film material

[0559] preliminary baking with 100° C. for 1 minutes

[0560] baking with 230° C. for 30 minutes

[0561] Thickness of orientation control film 500 Å

[0562] Irradiation conditions

[0563] 5 J/cm²

[0564] incident angle 15°

[0565] substrate temperature 23° C.

[0566] The whole substrate surface is irradiated through polarizingplate.

[0567] <Liquid Crystal>

[0568] Liquid crystal material:

[0569] nematic liquid crystal E31-LV manufactured by Merk & Co. andchiral agent S-811 (24.5 wt %) manufactured by Merk & Co.

[0570] Selective reflection peak wavelength: λ=550 nm

[0571] By observation with a polarization microscope, it was confirmedthat the liquid crystal near each orientation control film was in themixed state of the polydomain state and monodomain state.

[0572] In this experiment, the liquid crystal display element providedthe reflectance of 41% on the element observation side and the colorpurity of 80%, and exhibited high visibility at the front on the elementobservation side.

[0573] Although the view angle characteristics of this liquid crystaldisplay element is not shown in the figure, the reflectance at theobservation angle of 30° was 21%, and was 50% or more of the reflectanceat the observation angle of 0° so that it can be considered that theview angle characteristics were in a sufficiently practicable range.

[0574] When the focal conic state was attained by application of thepulse voltage, the Y-value of 1.2 was obtained immediately after thevoltage application, and the Y-value of 1.4 was obtained after onemonth. Thus, the liquid crystal display element of this experiment couldsuppress the change in display characteristics, and had the good memorycharacteristics.

Experimental Example 6

[0575] This experiment was performed with further another example of theliquid crystal display element of a single layer, in which theinclination (angle of the helical axis of the liquid crystal in theselective reflection state with respect to the substrate normal) of thehelical axis of the liquid crystal was different between the upper andlower substrates (i.e., the optical orientation processing was effectedon the orientation control films of the opposite substrates withdifferent temperatures of substrates during the exposure, respectively).

[0576] <Orientation Control Film on the Observation Side>

[0577] Orientation control film material:

[0578] polyimide

[0579] TT-054 (Hitachi Chemical Co., Ltd.)

[0580] Optical orientation was effected.

[0581] Inclination of helical axis (average):

[0582] about 12°

[0583] Deposition conditions:

[0584] flexo print of orientation control film material

[0585] preliminary baking with 100° C. for 1 minutes

[0586] baking with 230° C. for 30 minutes

[0587] Thickness of orientation control film 500 Å

[0588] Irradiation conditions

[0589] 2 J/cm²

[0590] incident angle 15°

[0591] substrate temperature 23° C.

[0592] The whole substrate surface was irradiated through a polarizingplate.

[0593] <Orientation Control Film on the Non-Observation Side>

[0594] Orientation control film material:

[0595] polyimide

[0596] TT-054 (Hitachi Chemical Co., Ltd.)

[0597] Optical orientation was effect.

[0598] Inclination of helical axis (average):

[0599] about 7°

[0600] Deposition conditions:

[0601] flexo print of orientation control film material

[0602] preliminary baking with 100° C. for 1 minutes

[0603] baking with 230° C. for 30 minutes

[0604] Thickness of orientation control film 500 Å

[0605] Irradiation conditions

[0606] 2 J/cm²

[0607] incident angle 15°

[0608] substrate temperature 120° C.

[0609] The whole substrate surface is irradiated polarizing plate.

[0610] <Liquid Crystal>

[0611] Liquid crystal material:

[0612] nematic liquid crystal E31-LV manufactured by Merk & Co. andchiral agent S-811 (24.5 wt %) manufactured by Merk & Co.

[0613] Selective reflection peak wavelength: λ=550 nm

[0614] By observation with a polarization microscope, it was confirmedthat the liquid crystal near each orientation control film was in themixed state of the polydomain state and monodomain state.

[0615] In this experiment, the liquid crystal display element providedthe reflectance of 40% on the element observation side and the colorpurity of 77%, and exhibited high visibility at the front on the elementobservation side.

[0616] Although the view angle characteristics of this liquid crystaldisplay element is not shown in the figure, the reflectance at theobservation angle of 30° was 21%, and was 50% or more of the reflectanceat the observation angle of 0° so that it can be considered that theview angle characteristics were in a sufficiently practicable range.

[0617] When the focal conic state was attained by application of thepulse voltage, the Y-value of 1.3 was obtained immediately after thevoltage application, and the Y-value of 1.5 was obtained after onemonth. Thus, the liquid crystal display element of this experiment couldsuppress the change in display characteristics, and had the good memorycharacteristics.

Experimental Example 7

[0618] This experiment was performed with still another example of theliquid crystal display element of a single layer, in which theinclination (angle of the helical axis of the liquid crystal in theselective reflection state with respect to the substrate normal) of thehelical axis of the liquid crystal was different between the upper andlower substrates (i.e., the partial rubbing was effected on theorientation control film of only one of the substrate)

[0619] <Orientation Control Film on the Observation Side>

[0620] Orientation control film material:

[0621] polyimide

[0622] JALS-1024-R (manufacture by JSR Corp.)

[0623] non-rubbing

[0624] Inclination of helical axis (average):

[0625] about 18°

[0626] Deposition conditions:

[0627] flexo print of orientation control film material

[0628] preliminary baking with 80° C. for 2 minutes

[0629] baking with 140° C. for 60 minutes

[0630] Thickness of orientation control film 500 Å

[0631] <Orientation Control Film on the Non-Observation Side>

[0632] Orientation control film material:

[0633] polyimide

[0634] JALS-1024-R (manufacture by JSR Corp.)

[0635] Partial rubbing was effect with the following resist pattern.

[0636] Inclination of helical axis (average):

[0637] about 7°

[0638] Deposition conditions:

[0639] flexo print of orientation control film material

[0640] preliminary baking with 80° C. for 2 minutes

[0641] baking with 140° C. for 60 minutes

[0642] Thickness of orientation control film 500 Å

[0643] Resist pattern

[0644] Photomask: non-opening/opening=7 μm/3 μm

[0645] (pitch 10 μm)

[0646] Spin coating of OFPR-800 (Tokyo Ohka Kogyo Co., Ltd.)

[0647] Prebake: 80° C. for 15 minutes, clean oven

[0648] Exposure: 30 mJ/cm² with UV exposing device

[0649] Development: SD-1 (developer manufactured by Tokuyama Corp.)

[0650] Rinsing: flowing ultrapure water

[0651] Post-bake: 120° C. for 15 minutes

[0652] Etching: iron-salt liquid D (manufactured by Hayashi PureChemical Ind., Ltd.) 20 minutes

[0653] Resist peeling: isopropyl alcohol (IPA: manufactured by TokuyamaCorp.), peeling time=2 minutes

[0654] Rubbing conditions

[0655] pressed brush height(pressed amount): 0.4 mm

[0656] roller radius: 75 mm

[0657] roller rotation speed: 900 rpm

[0658] substrate moving speed: 30 mm/sec

[0659] rubbing times: 2

[0660] rubbing density: about 470

[0661] <Liquid Crystal>

[0662] Liquid crystal material:

[0663] nematic liquid crystal E31-LV manufactured by Merk & Co. andchiral agent S-811 (24.5 wt %) manufactured by Merk & Co.

[0664] Selective reflection peak wavelength: λ=550 nm

[0665] By observation with a polarization microscope, it was confirmedthat the liquid crystal near the orientation control film on theobservation side was entirely in the polydomain state in the planarstate, and the liquid crystal near the orientation control film on thenon-observation side was in the mixed state of the polydomain state andmonodomain state.

[0666] In this experiment, the liquid crystal display element providedthe reflectance of 39% on the element observation side and the colorpurity of 72%, and exhibited high visibility at the front on the elementobservation side.

[0667] The view angle characteristics of this liquid crystal displayelement is not shown in the figure, but the reflectance at theobservation angle of 30° was 21%, and was 50% or more of the reflectanceat the observation angle of 0° so that it can be considered that theview angle characteristics were in a sufficiently practicable range.

[0668] When the focal conic state was attained by application of thepulse voltage, the Y-value of 1.3 was obtained immediately after thevoltage application, and the Y-value of 1.4 was obtained after onemonth. Thus, the liquid crystal display element of this experiment couldsuppress the change in display characteristics, and had the good memorycharacteristics. Further, an extremely high transmittance of about 80%was obtained in the focal conic state.

Experimental Example 8

[0669] This experiment was performed with an example of the multilayerliquid crystal display element formed of a plurality of single-layerliquid crystal display elements each configured such that theinclination (angle of the helical axis of the liquid crystal in theselective reflection state with respect to the substrate normal) of thehelical axis of the liquid crystal was different between the upper andlower substrates, and thus an example of the multilayer liquid crystaldisplay element, in which the respective elements were different fromeach other in angle of the helical axis of the liquid crystal in theselective reflection state with respect to the substrate normal.

[0670] <Substrate>

[0671] Substrate material: polycarbonate substrate with ITO

[0672] Thickness: 0.1 mm

[0673] <Liquid Crystal>

[0674] The peak wavelengths of the liquid crystal compositions in theselective reflection were adjusted by changing the amount of chiralmaterial added to the nematic liquid crystal.

[0675] Red display (R) element: adjusted to have the selectivereflection peak wavelength λ of 680 nm

[0676] cell gap=b 9 μm

[0677] Green display (G) element: adjusted to have the selectivereflection peak wavelength λ of 550 nm

[0678] cell gap=5 μm

[0679] Blue display (B) element: adjusted to have the selectivereflection peak wavelength λ of 480 nm

[0680] cell gap=5 μm

[0681] A black light absorber layer was arranged on the lowest surface(bottom surface of the substrate of R element) of the stacked structureof the liquid crystal optical modulation elements R, G and B.

[0682] In each of the layers of the liquid crystal elements, theorientation control films were made of the same combination of thematerials as that of the example 1, and each element was not subjectedto the rubbing, and was configured such that the inclination of thehelical axis on the observation side is larger than the inclination ofthe helical axis on the non-observation side. The inclination angle(angle of the helical axis of the liquid crystal in the selectivereflection state with respect to the substrate normal) of the helicalaxis of the liquid crystal depends on the helical pitch of thecholesteric liquid crystal, and decreases with increase in helicalpitch. The inclination angles of the liquid crystal display elements ofthe R, G and B layers were measured as follows:

[0683] R liquid crystal display element:

[0684] 16° on observation side and 5° on non-observation side

[0685] G liquid crystal display element:

[0686] 18° on observation side and 7°on non-observation side

[0687] B liquid crystal display element:

[0688] 20° on observation side and 8° on non-observation side

[0689] As compared with a multilayer liquid crystal display elementformed of liquid crystal display elements each configured such thatsubstantially no difference is present in inclination angle (equal toabout 18-20°) between the upper and lower substrates, the multilayerliquid crystal display element formed of the liquid crystal displayelements, each of which is configured such that a difference is presentin inclination angle between the upper and lower substrates, can improvethe color purity of each of the liquid crystal display element layer,and can improve the transmittance of the element. Therefore, the colorpurity is further improved in the multilayer liquid crystal displayelement formed of the liquid crystal display elements each having adifference in inclination angle between the upper and lower substrates.

[0690]FIG. 27 shows chromaticity diagrams of displayed images of themultilayer liquid crystal display element obtained in this experimentalexample and a multilayer liquid crystal display element (comparativeexample) having three layers of liquid crystal display elements eachhaving opposite substrates made of the same material (JALS-1024-Rmanufactured by JSR Corp.) and not subjected to the rubbing. In FIG. 27,solid line represents the chromaticity of the multilayer liquid crystaldisplay element of this experimental example, and dotted line representsthe chromaticity of the liquid crystal display element of thecomparative example. It can be seen from FIG. 27 that the multilayerliquid crystal display element of this experimental example can providea wider expressible color range.

Experimental Example 9

[0691] This example was performed with another example of the multilayerliquid crystal display element including liquid crystal display elementseach configured such that a difference was present in rubbing densitybetween the orientation control films.

[0692] <Substrate>

[0693] Substrate material: polycarbonate substrate with ITO

[0694] Thickness: 0.1 mm

[0695] <Liquid Crystal>

[0696] The peak wavelengths of the liquid crystal compositions in theselective reflection were adjusted by changing the amount of chiralmaterial added to the nematic liquid crystal.

[0697] Red display (R) element: adjusted to have the selectivereflection peak wavelength λ of 680 nm

[0698] cell gap=9 μm

[0699] Green display (G) element: adjusted to have the selectivereflection peak wavelength λ of 550 nm

[0700] cell gap=5 μm

[0701] Blue display (B) element: adjusted to have the selectivereflection peak wavelength λ of 480 nm

[0702] cell gap=5 μm

[0703] A black light absorber layer was arranged on the lowest surface(bottom surface of the substrate of R element) of the stacked structureof the liquid crystal optical modulation elements R, G and B.

[0704] <Orientation control film>

[0705] polyimide

[0706] JALS-1024-R (manufactured by JSR Corp.)

[0707] In each layer of the liquid crystal display element, theorientation control films for the upper and lower substrates were madeof the same material, In each layer of the liquid crystal displayelement, the orientation control film on the observation side was notsubjected to the rubbing, and the orientation control film on thenon-observation side was subjected to the rubbing. The rubbing densitywas controlled based on the rubbing times (N in the foregoing formula(1)). The rubbing times of the orientation control films on thenon-observation side in the R, G and B liquid crystal display elementswere set to 10, 5 and 3, respectively. The inclination angles (angles ofthe helical axes of the liquid crystal in the selective reflection statewith respect to the substrate normal) of the liquid crystal displayelements of the R, G and B layers were measured as follows:

[0708] R liquid crystal display element:

[0709] 16° on observation side and 3° on non-observation side

[0710] G liquid crystal display element:

[0711] 18° on observation side and 4° on non-observation side

[0712] B liquid crystal display element:

[0713] 20° on observation side and 6° on non-observation side

[0714] As compared with a multilayer liquid crystal display elementformed of liquid crystal display elements each configured such thatsubstantially no difference is present in inclination angle (equal toabout 18-20°) between the upper and lower substrates, the multilayerliquid crystal display element formed of the liquid crystal displayelements, each of which is configured such that a difference is presentin inclination angle between the upper and lower substrates, can improvethe color purity of the liquid crystal display element of each layerliquid, and can improve the transmittance of the element. Therefore, thecolor purity is further improved in the multilayer liquid crystaldisplay element formed of the liquid crystal display elements eachhaving a difference in inclination angle between the upper and lowersubstrates.

[0715]FIG. 28 shows a chromaticity diagram of a displayed image of themultilayer liquid crystal display element obtained in this experimentalexample. Similarly to FIG. 27, it can be seen from FIG. 28 that themultilayer liquid crystal display element of this experimental examplecan provide a wider expressible color range. In FIG. 28, dotted linerepresents the same chromaticity (dotted line) as shown in FIG. 27.

[0716] Description will now be given on experimental examples performedwith liquid crystal display elements, each of which was provided withregions having different orientation regulating force for regularlyorientating the helical axes of the liquid crystal molecules in thefocal conic state in a plane substantially parallel to the substratesurface.

Experimental Example 10

[0717] In this example, rubbing processing was effected on orientationcontrol films.

[0718] Two glass substrates with ITO (manufactured by Central Glass Co.,Ltd.) were used. Photolithography was effected on the ITO of eachsubstrate to pattern it into belt-like forms having an electrode widthof 300 μm and a pitch of 350 μm.

[0719] Then, an insulating material was applied to the ITO-surface ofeach substrate, and was baked to form the insulating film. Thereafter, apolyimide material AL-8044 (manufactured by JSR Corp.) was applied byflexo printing, and was preliminarily baked at 80° C. for two minutes.Further, baking was performed at 160° C. for 60 minutes so that theorientation control film was formed.

[0720] Then, positive resist OFPR-800 (manufactured by Tokyo Ohka KogyoCo., Ltd.) was applied by spin coating on orientation control film onone of the substrates, and was pre-baked at 80° C. for 15 minutes in aclean oven.

[0721] Using a photomask, which is provided with belt-like openings of 4μm in width at a pitch of 10 μm, exposure was performed at 30 mJ/cm² bya UV exposing device. Then, development was performed with developerliquid (SD-1 manufactured by Tokuyama Corp.), and rising was performedwith flowing ultrapure water for removing unnecessary portions.Thereafter, post-baking was performed at 120° C. for 15 minutes. In thismanner, the mask layer was formed for the next rubbing processing.

[0722] Then, rubbing processing was effected on the substrate coatedwith the mask layer. The rubbing processing was effected two timesthrough the mask layer by a brush roll with a pressed brush height(pressed amount) of 0.4 mm and a roller radius of 75 mm under theconditions of the roller rotation speed of 900 rpm and the substratemoving speed of 30 mm/sec. The rubbing density was about 470, and theaverage helical axis inclination was about 5°.

[0723] After the rubbing, the resist peeling was performed withisopropyl alcohol (IPA) for two minutes to remove the mask layer.Spacers (Micropearl SP2050 manufactured by Sekisui Chemical Co., Ltd.)of 5 μm were dispersed on the substrate thus rubbed, and a seal agent(XN21S manufactured by Mitsui Chemicals Co., Ltd.) was applied to theother substrate while leaving the liquid crystal inlet. These substrateswere bonded together to form an empty cell.

[0724] As the liquid crystal composition, such chiral nematic liquidcrystal was used that was formed of nematic liquid crystal E31-LVmanufactured by Merk & Co. and chiral agent S-811 (24.5 wt %)manufactured by Merk & Co., and had the selective reflection peakwavelength λ adjusted to 550 nm. The liquid crystal composition had thehelical pitch of about 343 nm. The liquid crystal composition wassupplied into the cell by a vacuum-supply method. Finally, the liquidcrystal inlet was closed by a seal agent to complete the liquid crystallight modulation element.

[0725] The liquid crystal light modulation element thus prepared was setto the focal conic state by applying a voltage, and then thecharacteristics of the element were evaluated. The evaluation was madewith a spectrophotometer (Hitachi Ltd.) by measuring the transmissivity(transmittance) while keeping a space from an integrating sphere. Thetransmittance of the element thus measured was about 80%. Forcomparison, a liquid crystal display element was prepared in the samemanner as the experimental example 10 except for that the rubbing wasnot performed. This element in the focal conic state had thetransmittance of about 62%.

[0726] The width and arrangement pitch of the rubbing processingportions were changed to various values for determining the influencesthereof. There was a tendency that the transmissivity (transmittance)lowers when the above width and pitch excessively increase or decreasebeyond the ranges defined by (p<W<20p) where W represents the width ofthe region of the different orientation regulating force, and prepresents the helical pitch of the liquid crystal, and defined by(5p<L<100p) where L represents the arrangement pitch of the regions ofthe different orientation regulating force.

[0727] The element provided with the rubbing processing portions of theuniform arrangement pitch as well as the element provided with therubbing processing portions arranged randomly were prepared fordetermining the influences of the arrangements. According to the result,these elements exhibited the transmittances of similar values. However,in the element of the uniform arrangement pitch, diffracted light wasobserved in a specific angle, and there was a tendency that thevisibility lowers.

[0728] Further, the arrangement direction of the rubbing processedportions and the pixel arrangement direction were changed variously, andthe influences thereof were determined. The transmittances weresubstantially uniform. However, in the case where these two kinds ofdirections are the same, moire phenomenon was likely to occur todeteriorate the display quality.

[0729] Such elements were prepared that were provided with the rubbingprocessing portions having a straight form and a dogleg form,respectively. The transmittances were substantially uniform in theseelements. However, the rubbing processing portion of the straight formwas likely to provide the visibility of different degrees depending onthe directions of observation, i.e., the same direction as thearrangement direction of the rubbing processing portions and thedirection perpendicular to the arrangement direction.

[0730] As compared with the element not subjected to the rubbingprocessing, a significant change was not found in the memorycharacteristics. Also, it was confirmed that 50% or more of the viewangle characteristics was ensured, and the front reflectance wasincreased.

Experimental Example 11

[0731] In this example, optical orientation processing was effected onorientation control films.

[0732] Two glass substrates with ITO (manufactured by Central Glass Co.,Ltd.) were used. Photolithography was effected on the ITO of eachsubstrate to pattern it into belt-like forms having an electrode widthof 300 μm and a pitch of 350 μm.

[0733] Then, the insulating films were formed on the ITO-coated surfacesof the opposite substrates in the following manner. Polysilazanesolution L120 (manufactured by Tonen Corp.) was used, and a thin filmthereof having a thickness of 1000 Å was formed on the electrode surfaceof each substrate by the spin coat method. The film was heated in aconstant temperature oven at 120° C. for 2 hours, and further, washeated in the constant temperature over at a temperature of 90° C. and ahumidity of 85% for 3 hours. Thereafter, a polyimide material (TT-054manufactured by Hitachi Chemical Co., Ltd.) was applied by spin coatingunder the conditions of 3000 rpm and 30 seconds, and was preliminarilybaked at 100° C. for one minute. Further, baking at 230° C. for 30minutes was performed to complete the orientation control film.

[0734] The orientation control film on one of the substrates wassubjected to the partial orientation processing, which was effectedthrough a photomask provided with opening portions similar to that ofthe experimental example 10 and a polarizing plate by the UV irradiationdevice with 5 J/cm² and the incident angle of 15°. The inclination angleof the helical axis was about 7°.

[0735] Thereafter, the spacer dispersion, sealing formation, substratebonding and liquid crystal supply were performed in the manner similarto that of the experimental example 10 so that the liquid crystaldisplay element was completed.

[0736] The liquid crystal light modulation element thus prepared was setto the focal conic state by applying a voltage, and then measurement wasperformed similarly to the experimental example 10. The transmittance ofthe element thus measured was about 80%.

[0737] Results similar to those of the experimental example 10 wereobtained. Thus, such tendencies were determined that the transmittancelowers when the width and arrangement pitch of the optical processingportion excessively increase or decrease beyond the foregoing ranges,that the uniform arrangement pitch of the optical processing portionsprovides similar transmittances, but was likely to lower the visibilitydue to the influence by diffracted light, that the arrangement directionof the optical orientation processing portion equal to the pixelarrangement direction provides similar transmittances, but was likely tolower the display quality due to the influence by moire, and that thestraight arrangement of the optical orientation processing portionsprovides similar transmittances, but was likely to cause a difference invisibility between the observation directions parallel and perpendicularto the arrangement direction.

[0738] As compared with the element not subjected to the opticalorientation processing, a significant change was not found in the memorycharacteristics. Also, it was confirmed that 50% or more of the viewangle characteristics was ensured, and the front reflectance wasincreased.

[0739] (3) With Respect to Sixth Liquid Crystal Light (Optical)Modulation Element and Third Element Producing Method

[0740] (3-1) Sixth Element

[0741] A sixth liquid crystal light (optical) modulation element is aliquid crystal light modulation element for performing light (optical)modulation by utilizing a focal conic state of liquid crystal moleculesincluded in a liquid crystal layer held between a pair of substrates,wherein helical axes of the liquid crystal molecules in the focal conicstate extend in regular directions within a plane substantially parallelto a substrate surface.

[0742] In this element, since the helical axes of the liquid crystalmolecules in the focal conic state extend in regular directions within aplane substantially parallel to the substrate surface, the transmittance(transmissivity) of the liquid crystal layer in the focal conic state isremarkably improved, and the liquid crystal light modulation element canhave high contrast.

[0743] Orientation regulating means may be employed in the element fororientating the helical axes of the liquid crystal molecules in thefocal conic state in regular directions within a plane substantiallyparallel to the substrate surface.

[0744] The orientation regulating means can orientate the helical axesof the liquid crystal molecules in the focal conic state along regulardirections when a predetermined voltage is applied across thesubstrates. In this case, anisotropy (or distortion) may be caused inthe electric field directions (in other words, lines of electric forceof the electric field or equal potential lines of the electric field)for orientating the helical axes of the liquid crystal molecules inregular directions.

[0745] The orientation regulating means may be a projected structureformed on at least one of the substrates for causing the anisotropy inthe directions of the electric field by the projected structure. Theprojected structure has such a feature that the regulating force to theliquid crystal molecules can be easily increased.

[0746] The projected structure may be a rib-like form. By employing therib-like form, the regulating force to the liquid crystal molecules canbe expanded toward the substrate surface. The projected structure mayhave a side surface inclined with respect to the direction of thesubstrate normal (normal line). This inclination can smoothen the equalpotential lines when the electric field is applied, and can suppressirregularities in the regulating force to the liquid crystal molecules.A pixel electrode may be formed on the substrate, and the projectedstructure may be formed on the pixel electrode.

[0747] A height h of the projected structure and a gap d between thesubstrates preferably satisfy a relationship of:

d/20<h<d/2

[0748] By keeping the height h of the projected structure in the aboverange, it is possible keep an appropriate regulating force to the liquidcrystal molecules and an appropriate effective gap between thesubstrates while preventing lowering of the reflection intensity in theplanar state.

[0749] A width W of the projected structure and a helical pitch p of theliquid crystal preferably satisfy a relationship of:

p<W<20p

[0750] An arrangement pitch L of the projected structures and a helicalpitch p of the liquid crystal preferably satisfy a relationship of:

5p<L<100p

[0751] By employing the width W and arrangement pitch L of the projectedstructures within the above ranges, a sufficient regulating force can bekept for the liquid crystal molecules while preventing lowering of adisplay opening rate and complication of the element producing steps.

[0752] The arrangement pitch of the projected structures may not beuniform within the above range. By employing the arrangement pitch ofthe projected structures, which is not uniform, it is possible tosuppress lowering of the visibility due to light diffraction phenomenon.

[0753] The display element may include a plurality of pixels. In thiscase, a direction of arrangement of the projected structures may bedifferent from a direction of arrangement of the pixels. Also, theelement may include a plurality of regions which are different indirection of arrangement of the projected structures. Thereby, thevisibility does not depend on the light incident direction, and uniformlight transmission characteristics can be achieved.

[0754] An electrode may be formed on the substrate, and the anisotropy(or distortion) may be caused in the electric field directions (in otherwords, lines of electric force of the electric field or the like) by agroove, which serves as orientation control means and is formed on theelectrode on at least one of the substrates. Formation of the groove onthe electrode does not require addition of a new member in the liquidcrystal element, and thus improves the reliability. Since the groove canbe formed simultaneously with the patterning of the electrode, theproducing steps can be simple, and the possibility of mixing ofimpurities and dust can be low.

[0755] A width W of the groove and a helical pitch p of the liquidcrystal preferably satisfy a relationship of:

p<W<20p

[0756] An arrangement pitch L of the grooves on the electrode(s) and thehelical pitch p of the liquid crystal preferably satisfy a relationshipof:

5p<L<100p

[0757] By employing the width W and arrangement pitch L of the grooveson the electrode within the above ranges, a sufficient regulating forcecan be kept for the liquid crystal molecules and complication of theelement producing steps can be suppressed.

[0758] The arrangement pitch L of the electrode grooves may not beuniform within the above range. By employing the arrangement pitch ofthe electrode grooves, which is not uniform, it is possible to suppresslowering of the visibility due to light diffraction phenomenon.

[0759] A direction of arrangement of the electrode grooves may bedifferent from a direction of arrangement of the pixels. Also, theelement may include a plurality of regions which are different indirection of arrangement of the grooves. Thereby, the visibility doesnot depend on the light incident direction, and uniform lighttransmission characteristics can be achieved.

[0760] An insulating film may be formed on at least one of thesubstrates, and the anisotropy may be caused in the electric fielddirections by a groove, which serves as orientation control means and isformed on the insulating film on at least one of the substrates.Formation of the groove on the insulating film does not require additionof a new member in the liquid crystal element, and thus improves thereliability.

[0761] A width W of the groove on the insulating film and a helicalpitch p of the liquid crystal preferably satisfy a relationship of:

p<W<20p

[0762] An arrangement pitch L of the grooves on the insulating film andthe helical pitch p of the liquid crystal preferably satisfy arelationship of:

5p<L<100p

[0763] By employing the width W and arrangement pitch L of the grooveson the insulating film within the above ranges, a sufficient regulatingforce can be kept for the liquid crystal molecules and complication ofthe element producing steps can be suppressed.

[0764] The arrangement pitch L of the electrode grooves on theinsulating film may not be uniform within the above range. By employingthe arrangement pitch of the grooves on the insulating film, which isnot uniform, it is possible to suppress lowering of the visibility dueto light diffraction phenomenon.

[0765] A direction of arrangement of the grooves on the insulating filmmay be different from a direction of arrangement of the pixels. Also,the element may include a plurality of regions which are different indirection of arrangement of the grooves. Thereby, the visibility doesnot depend on the light incident direction, and uniform lighttransmission characteristics can be achieved.

[0766] Regions providing a different orientation regulating force may bearranged partially on a surface of at least one of the substrates incontact with the liquid crystal for orientating helical axes of theliquid crystal molecules in a regular direction. By arranging theregions of the different orientation regulating force, the direction ofthe helical axis is determined by the difference in surface regulatingforce during transition of the liquid crystal molecules to the focalconic state. Therefore, the helical axes of the liquid crystal can beregularly orientated, similarly to the manner of inclining the directionof the electric field.

[0767] The region having the different orientation regulating force maybe formed by partially effecting the rubbing, partially effecting thelight irradiation or using a partially different material.

[0768] A width W of the region having the different orientationregulating force and a helical pitch p of the liquid crystal may satisfya relationship of:

p<W<20p

[0769] An arrangement pitch L of the regions of the differentorientation regulating force and the helical pitch p of the liquidcrystal preferably satisfy a relationship of:

5p<L<100p

[0770] By employing the width W and arrangement pitch L of the regionshaving the different orientation regulating force within the aboveranges, a sufficient regulating force can be kept for the liquid crystalmolecules and complication of the element producing steps can beprevented.

[0771] The arrangement pitch of the regions having the differentorientation regulating force may not be uniform within the above ranges.By employing the arrangement pitch of the regions having the differentorientation regulating force, which is not uniform, it is possible tosuppress lowering of the visibility due to light diffraction phenomenon.

[0772] A plurality of pixels may be arranged in a direction differentfrom a direction of arrangement of the regions having the differentorientation regulating force. Also, the element may include a pluralityof regions which are different in direction of arrangement of theregions having the different orientation regulating force. Thereby, thevisibility does not depend on the light incident direction, and uniformlight transmission characteristics can be achieved.

[0773] A multilayer liquid crystal light (optical) modulation elementmay be formed of a plurality of liquid crystal light modulation elementsstacked together and having the same structure as the element describedabove.

[0774] A multilayer liquid crystal light modulation element may includeany one of the foregoing elements as well as an element stacked togetherwith the above element and containing liquid crystal molecules, whichhave helical axes extending irregularly in a plane parallel to asubstrate when being in the focal conic state.

[0775] At least the element on the end of the front side may be any oneof the foregoing element. In any one of the above cases, stacking of theplurality of liquid crystal layers increases the scattering components,and thereby can effectively suppress the increase in transmittance inthe focal conic state.

[0776] The liquid crystal exhibiting the focal conic state may be liquidcrystal exhibiting a cholesteric phase at a room temperature. In thiscase, the liquid crystal exhibiting the cholesteric phase at a roomtemperature may be liquid crystal having positive dielectric anisotropy.

[0777] In each of the above elements, display may be performed byswitching the liquid crystal between the focal conic state and theplanar state. In this case, the liquid crystal in the planar state mayhave a peak of selective reflection in a visible wavelength range.

[0778] In the multilayer liquid crystal light modulation element, thestacked elements may have different peak wavelengths of selectivereflection, respectively, in which case display in multicolor can beperformed. Also, at least two liquid crystal elements having differentoptical rotation directions, respectively, may be employed, in whichcase the light utilizing efficiency can be increased. The liquid crystallayers having different optical rotation directions may have asubstantially equal peak wavelength of selective reflection, in whichcase the reflectance of the liquid crystal layer(s) can be increased.

[0779] An example of the third method of producing the liquid crystallight (optical) modulation element will now be described.

[0780] (3-2) Third Method of Producing the Liquid Crystal Light(Optical) Modulation Element

[0781] A third method is a method of producing a liquid crystal light(optical) modulation element for performing light modulation byutilizing a focal conic state of liquid crystal molecules included in aliquid crystal layer held between a pair of substrates.

[0782] This method includes the steps of providing orientationregulating means (e.g., a projected structure, a groove in an electrodeformed on the substrate, an insulating film having a groove and formedon the substrate, a region on the substrate providing partiallydifferent orientation regulating force) for regularly orientatinghelical axes of the liquid crystal molecules in the focal conic state onat least one of the substrates, and a step of arranging the liquidcrystal layer between the paired substrates.

[0783] Examples of the third producing method of the liquid crystallight modulation element will now be described.

[0784] An example of the element producing method belonging to this typeof element producing method includes the steps of providing a projectedstructure for regularly orientating helical axes of the liquid crystalmolecules in the focal conic state on at least one of the substrates,and a step of arranging the liquid crystal layer between the pairedsubstrates including the substrate(s) provided with the projectedstructure.

[0785] The form, position, height, arrangement pitch, arrangementdirection and others of the projected structure(s) for regulating theorientation of the liquid crystal can be freely determined. Therefore,the orientation regulation of the liquid crystal can be easilycontrolled.

[0786] The projected structure may be formed by a photolithography.

[0787] Another example of the element producing method includes thesteps of forming pixel electrodes on the paired substrates,respectively, forming a groove on the electrode of at least one of thesubstrates for regularly orientating helical axes of liquid crystalmolecules in the focal conic state, and arranging the liquid crystallayer between the paired substrates including the substrate(s) providedwith the groove.

[0788] The form, position, depth, arrangement pitch, arrangementdirection and others of the groove(s) on the electrode for regulatingthe orientation of the liquid crystal can be freely determined.Therefore, the orientation regulation of the liquid crystal can beeasily controlled. This method does not require a step of providing anadditional member for orientation regulation of the liquid crystal.

[0789] The groove on the electrode may be formed by a photolithography.In this case, the patterning of the electrode for forming the pixels maybe performed simultaneously with the formation of the groove.

[0790] Still another example of the element producing method includesthe steps of forming on at least one of the paired substrates aninsulating film having a groove for regularly orientating helical axesof liquid crystal molecules in the focal conic state, and arranging theliquid crystal layer between the paired substrates including thesubstrate(s) provided with the insulating layer.

[0791] The form, position, depth, arrangement pitch, arrangementdirection and others of the groove(s) on the insulating film forregulating the orientation of the liquid crystal can be freelydetermined. Therefore, the orientation regulation of the liquid crystalcan be easily controlled. This method does not require a step ofproviding an additional member for orientation regulation of the liquidcrystal.

[0792] The groove on the insulating film may be formed by aphotolithography.

[0793] Yet another example of the element producing method includes thesteps of partially forming on a surface, in contact with the liquidcrystal, of at least one of the substrates a region having a differentorientation regulating force for regularly orientating helical axes ofliquid crystal molecules in the focal conic state, and arranging theliquid crystal layer between the paired substrates including thesubstrate(s) provided with the region having the different orientationregulating force.

[0794] The form, position, arrangement pitch, arrangement direction andothers of the region(s) having the different orientation regulatingforce can be freely determined. Therefore, the orientation regulation ofthe liquid crystal can be easily controlled. This method does notrequire a step of providing an additional member for orientationregulation of the liquid crystal.

[0795] The above region may be formed by partially effecting rubbing orby partially effecting light irradiation.

[0796] The step of partially forming the region(s) having the differentregulating force may include the steps of arranging a mask layerprovided with an opening on the substrate, and removing the mask layer.

[0797] The region having the different regulating force may be formed byforming an orientation film having a partially different kind ofmaterial.

[0798] (3-3) With respect to the Liquid Crystal Light (Optical)Modulation Element and Others Shown in the Figures

[0799] The liquid crystal light modulation element of the foregoing typeand others will now be described with reference to FIGS. 30-45.

[0800] (Examples of Basic Structure of the Liquid Crystal Light(Optical) Modulation Element, see FIGS. 30(a)-30(d))

[0801] FIGS. 30(a)-30(d) are cross sections each showing an example ofthe liquid crystal display element. Description will now be given on thebasic structure of the liquid crystal light modulation element withreference to FIG. 30(a). As shown in FIG. 30(a), two transparentsubstrates 10′ provided with transparent electrodes 11′ are arranged. Aliquid crystal material 25 and spacers 20 for controlling the gap arearranged between the substrates 10′ with the electrodes 11′. A seal 19′is continuously arranged on the periphery except for a liquid crystalinlet. In FIG. 30(a), only one end of the element is shown. A lightabsorber layer 30 is arranged on the rear side of the element.

[0802] The transparent substrate may be a glass substrate, or may be aflexible resin substrate made of, e.g., polycarbonate, polyether sulfone(PES) or polyethylene terephthalate. If the liquid crystal lightmodulation element is to be used as the element of the reflection typeor the optical writing type, one of the substrates may not betransparent.

[0803] The transparent electrode 11′ formed on the transparent substrate101 for controlling the liquid crystal light modulation element may beformed of a transparent conductive film made of ITO (Indium Tin Oxide)or the like, a metal electrode made of, e.g., aluminum or silicon, or aphotoconductive film made of, e.g., amorphous silicon or BSO. It is alsopossible to use an electrode structure of an active matrix type, whichincludes a plurality of pixel electrodes and thin-film transistorsconnected thereto. An electrode, which serves also as the substrate byitself, can be used.

[0804] If necessary, an orientation film made of, e.g., polyimide may bearranged on the electrode formation surface of the substrate 10′, ororganic and inorganic films may be arranged thereon as a gas barrierlayer and/or an insulating layer for improving the reliability of theliquid crystal light modulation element. FIG. 30(a) and others show anexample, in which an insulating film 18′ and an orientation film 11′ arearranged on each of the substrates.

[0805] The spacers 20 may be spherical particles made of glass, plasticsor the like.

[0806] The seal 19′ may be made of various material provided that theliquid crystal composition can be supplied into the liquid crystalelement, and is preferably made of ultraviolet-curing resin orthermosetting resin. In particular, the thermosetting resin such asepoxy resin may be used as the seal resin, whereby high gas-tightnesscan be kept for a long term.

[0807] By applying a voltage across the electrodes 12′ arranged on thesubstrates 10′, the liquid crystal can be changed from the planar stateto the focal conic state, and vice versa.

[0808] The liquid crystal material 25 may be of the type, which allowsutilization of the focal conic state for light modulation, and may becholesteric liquid crystal or chiral nematic liquid crystal prepared byadding a chiral agent to nematic liquid crystal for exhibiting acholesteric phase at a room temperature. In any one of the above cases,the liquid crystal material having positive dielectric anisotropy can beemployed.

[0809] The focal conic state is such a state that the liquid crystalmolecules are orientated parallel to each other so that the helical axesof the liquid crystal may be parallel to both the upper and lowersubstrate surfaces. Usually, the directions of the helical axes are notuniform in the focal conic state.

[0810] For holding the liquid crystal material between the pairedsubstrates, a known vacuum-supply method or a liquid crystal droppingmethod may be appropriately used depending on the intended size of theliquid crystal element and the gap between the substrates.

[0811] As shown in FIG. 36, the element may be provided with a structure28, which is in surface-contact with the upper and lower substrates 10′(and preferably is bonded to the upper and lower substrates). Thisstructure improves the accuracy of the gap between the substrates.Particularly, in the structure having the substrates bonded together, itis possible to prevent the increase in distance between the substrates,and the structure is effective for the substrates formed of resin films.The structure 28 may be made of various resin materials.

[0812] The projected structure shown in FIG. 30(a), the groove formed onthe insulating film shown in FIG. 30(b), the groove formed on thetransparent electrode shown in FIG. 30(c) and the regions having thedifferent orientation regulating force in FIG. 30(d) correspond to theregion, which regulates the helical axes of the liquid crystal in thefocal conic state, and will be referred to as an “orientation regulatingregion” hereinafter. This will now be described in greater detail.

[0813] It is already confirmed that the effect achieved by regularlyarranging the direction of the helical axes is not significantlyaffected by the manner of holding the liquid crystal, the kind of thespacer 20, the present/absence of the structure 28 and the like.

[0814] (Manner of Regulating Helical Axis Direction, see FIGS. 31-35)

[0815] (1) Manner Utilizing Control of the Electric Field

[0816] A manner of utilizing control of the electric field may be one ofthe manners of regularly orientating the helical axes in a planesubstantially parallel to the substrate. This method utilizing thecontrol of the electric field will now be described.

[0817] For example, as shown in FIG. 30(a), a projected structure 13′ ofthe rib form is arranged on the substrate 10′. The provision of theprojected structure 13′ causes distortion in the equal potential lines26 near the projected structure 13′ when a voltage is applied across theelectrodes 12′ as shown in FIG. 31. Therefore, the electric fielddirections 27 (in other words, lines of electric force in the electricfield) are partially inclined to specific directions as shown in FIG.32. When the application of the voltage is stopped in the above statefor changing the liquid crystal to the focal conic state, the influenceof the inclined electric field, which was previously present, restrictsthe direction of the helical axes of the liquid crystal. As a result,the helical axes 22 of the liquid crystal are regularly orientated in aplane substantially parallel to the substrate, as shown in FIGS. 33 and34. Accordingly, it is possible to achieve the focal conic state, inwhich the helical axes 22 of the liquid crystal molecules are regularlyorientated, and therefore the light scattering is suppressed.

[0818] As shown in FIG. 30(b), the groove 14′ is formed on theinsulating film 181 likewise causes inclination of the electric field sothat it is possible to achieve the focal conic state, in which thehelical axes are uniformly orientated, and the light scattering issuppressed.

[0819] As shown in FIG. 30(c), the groove 15′ formed on the transparentelectrode 12′ causes the distortion in the potential lines 26 near thegroove 15′ as shown in FIG. 35, and therefore it is possible for thesame reason to achieve the focal conic state, in which the helical axesare regularly orientated, and the scattering is suppressed.

[0820] (1-a) Projected Structure

[0821] If the projected structure is formed by the photolithography, itmay be made of positive type photoresist such as novolac resin, or anegative type photoresist such as acrylic resin. If the printing methodis employed, the projected structure may be made of a thermosettingresin such as epoxy resin, a thermoplastic resin such as a polyurethaneresin, polyvinylchloride resin, or glass paste printed on the substrateby a known printing method.

[0822] If the substrates for holding the liquid crystal layer are formedof resin film substrates, convexities and concavities may be formed onthe substrate itself, and the electrode may be formed on the filmsubstrate, whereby the substrate provided with the projected structurescan be obtained in an easy manner. The convexities and concavities maybe formed on the film substrate itself by a mold method using a moldingdie pressed to the substrate.

[0823] The manner, in which the projected structures are used toorientate regularly the helical axes in a plane substantially parallelto the substrate, has such an advantage that the regulating force to theliquid crystal molecules can be easily increased.

[0824] It is desirable that the projected structure exerting theregulating force to the helical axis is formed on the transparentelectrode. The height of the projected structure is an importantparameter determining the direction of the helical axis. Assuming thatthe gap between the substrates is d, and the height of the projectedstructure is h, it is desirable that the height h satisfies arelationship of (d/20<h<d/2). If the height h of the projected structureis larger than the range of the above relationship, the effective gapbetween the substrates lowers so that the display brightness lowers inthe planar state when observed as the cholesteric liquid crystal displayelement. If the height h of the projected structure is low, theregulating force lowers, and an effect of uniformly orientating thehelical axes cannot be achieved.

[0825] The height of the projected structure can be arbitrarilyadjusted, e.g., by changing the spin coat rotation speed or thethickness of the form plate.

[0826] The form of the projected structure forms an important factor. Itis desirable that the side surface thereof is inclined with respect tothe substrate normal for obtaining smooth potential lines 26 as shown inFIG. 31.

[0827] For inclining the side surface of the projected structure formedon the substrate with respect to the substrate normal, such a manner maybe employed that a heat treatment is effected on the projected structurefor melting the surface thereof so that the inclination may be formed.

[0828] FIGS. 37(a)-37(f) show an example of formation of the projectedstructures. This example includes the following steps.

[0829] In FIG. 37(a), a resist film 40 is formed on an electrode surfaceof the substrate 10′ provided with a pattern of the electrode 12′.

[0830] In FIG. 37(b), the resist film 40 is exposed to a light source601 through openings 63′ in a mask 621.

[0831] In FIG. 37(c), development and rinsing are performed to removeunnecessary portions of the resist film 40 to form the projectedstructures 131.

[0832] In FIG. 37(d), a heat treatment or the like is performed on theprojected structures 131 to provide inclination of the side surfacesthereof.

[0833] In FIG. 37(e), the insulating film 181 is formed on the surfaceof the substrate 10′ provided with the projected structures 13′.

[0834] In FIG. 37(f), an orientation film 111 is formed on theinsulating film 181.

[0835] Through the above steps, the projected structures 131 of anintended form can be formed in the intended positions.

[0836] (1-b) Groove on the electrode

[0837] The groove can be formed by a known photolithography. Thephotolithography facilitates the formation of the groove(s), and allowsformation of the groove(s) simultaneously with formation of the pixelelectrodes so that the steps can be simplified. The groove(s) may beformed on only one or both of the substrates.

[0838] The manner, in which the groove is formed on the electrode forregularly orientating the helical axes in a plane substantially parallelto the substrate, allows formation of the groove simultaneous with thepatterning of the electrode so that the producing steps can be simple.Also, the possibility of mixing of impurities and dust can be low. Sincethis manner does not require addition of a new member in the liquidcrystal element, the reliability can be improved.

[0839] FIGS. 38(a)-38(g) show an example of formation of the grooves onthe electrode. This example includes the following steps.

[0840] In FIG. 38(a), the resist film 40 is formed on the electrodelayer 121 formed on the substrate 10′.

[0841] In FIG. 38(b), the resist film 40 is exposed to the light source60′ through the openings 63′ in the mask 62′.

[0842] In FIG. 38(c), development and rinsing are performed to removeunnecessary portions of the resist film 40 to form the openings 41 inthe resist film 40.

[0843] In FIG. 38(d), etching is effected on the electrode layer 12′,and the electrode layer 12′ is patterned into belt-like forms so thatthe grooves 15′ are formed.

[0844] In FIG. 38(e), the resist film 40 is removed.

[0845] In FIG. 38(f), the insulating film 18′ is formed on the substrate10′.

[0846] In FIG. 38(g), the orientation film 11′ is formed on theinsulating film 18′.

[0847] Through the above steps, the grooves 15′ of an intended form canbe formed in the intended positions by a relatively simple manner.

[0848] (1-c) Groove on the Insulating Film

[0849] For forming the groove on the insulating film, thephotolithography can be employed using a photosensitive resin materialas the material of the insulating film. The resin material, whichexhibits a larger difference in dielectric constant with respect to theliquid crystal material, can achieve a higher effect, and can beselected from various materials depending on the liquid crystalmaterial. The grooves may be formed on either or both of the insulatingfilms on the opposite substrates depending on the used liquid crystalmaterial.

[0850] The manner, in which the groove is formed on the insulating filmfor regularly orientating the helical axes in a plane parallel to thesubstrate, does not require addition of a new member in the liquidcrystal display element, and therefore can improve the reliability.

[0851] FIGS. 39(a)-38(d) show an example of the steps of forming thegrooves on the insulating film. This example includes the followingsteps:

[0852] In FIG. 39(a), a resist film 42 is formed on the electrodesurface of the substrate 101 provided with a pattern of the electrode12′.

[0853] In FIG. 39(b), the resist film 42 is exposed to the light source60′ through the openings 63′ in the mask 621.

[0854] In FIG. 39(c), development and rinsing are performed to removeunnecessary portions of the resist film 42 to form the openings in theresist film 42. Hardening processing is effected on the resist film 42to form the insulating film 181. The opening forms the groove 14′ on theinsulating film 181.

[0855] In FIG. 39(d), the orientation film 11 is formed on the surfaceprovided with the insulating film 18′.

[0856] Through the above steps, the grooves 14′ of an intended form canbe formed in the intended positions by a relatively simple manner.

[0857] (2) Manner by Employing Different Orientation Regulating Force

[0858] A method of forming a portion providing a different orientationregulating force may be used as another means for orientating thehelical axes regularly in the plane substantially parallel to thesubstrate. The portion providing the different orientation regulatingforce may be a region, which an anchoring force or an orientating forcewith respect to the liquid crystal molecules is different. The portionof the different orientation regulating force can be formed by, e.g.,effecting rubbing processing or optical orientation processing withultraviolet light or the like on the orientation film of, e.g.,polyimide uniformly coating the electrode surface. Also, by forming theorientation film made of a partially different kind of material, theportion providing the different orientation regulating force can beachieved. FIG. 30(d) shows an example, in which portions 16′ providing adifferent orientation regulating force are formed in the orientationfilm 11′.

[0859] The manner of forming the portion providing the differentorientation regulating force does not cause such a situation that therubbing processing or the like causes inclination in the electric fielddirection, but causes such a situation that the difference in surfaceregulating force determines the direction of the helical axes duringtransition of the liquid crystal molecules to the focal conic state, andthereby the effect similarly to that of the foregoing manner ofinclining the electric field direction can be achieved.

[0860] In the method of partially effecting the rubbing processing onthe orientation control film, a photoresist material is applied, e.g.,by spin coating to the orientation film, and then is removed from theportion to be rubbed by conventional photolithography, and then therubbing is performed. Thereafter the resist is removed. The rubbingdirection is not restricted.

[0861] In the case of the optical orientation, the portion having thedifferent orientation regulating force can be easily formed byperforming ultraviolet light exposure through the photomask and thepolarizing plate.

[0862] FIGS. 40(a)-40(d) show an example of the steps of forming theportion having the different orientation regulating force. This exampleincludes the following steps:

[0863] In FIG. 40(a), the insulating film 18′ is formed on the electrodesurface of the substrate 10′ provided with a pattern of the electrode12′.

[0864] In FIG. 40(b), the orientation film 11′ is formed on theinsulating film 18′.

[0865] In FIG. 40(c), the orientation film 11′ is exposed to the lightsource 60′ through the openings 63′ in the mask 62′, or

[0866] In FIG. 40(c′), the resist film 40 is formed on the orientationfilm 18′, and is patterned. Rubbing processing 64′ is effected on theorientation film 11′ through the openings 41 in the resist film 40.

[0867] Thereafter, the resist film is removed.

[0868] In FIG. 40(d), the regions 16′ having the different orientationregulating force are formed.

[0869] Through the above steps, the regions 161 having an intended formand providing the different orientation regulating force can be formedin the intended positions by a relatively simple manner.

[0870] For forming the different kind of orientation film portions, adifferent kind of orientation film material may be applied and bakedafter the patterning of the resist film in the step shown in FIG. 40(c),and then the resist film may be removed.

[0871] In any one of the above cases, the manner of effecting theorientation processing for regularly orientating the helical axes in aplane substantially parallel to the substrate does not require additionof a new member in the liquid crystal display element, and therefore canimprove the reliability. In particular, the optical orientationprocessing is superior in view of the fact that the possibility ofmixing of dust and others is low.

[0872] (3) Arrangement of Orientation Regulating Regions (see FIGS.41(a)-41(c))

[0873] In the methods described above, the regulating force of theregion having the same for uniformly orientating the helical axes isexerted only to a limited range, and therefore it is preferable that awidth W of the region and a helical pitch p of the liquid crystalmolecules satisfy a relationship of p<W<20p. An arrangement pitch L ofthe orientation regulating regions and the helical pitch p of the liquidcrystal molecules preferably satisfy a relationship of 5p<L<100p. If theabove pitch L is larger than the above range, larger region notsubjected to the regulating force is likely to be formed, and thescattering between the domains increases in the focal conic state. Ifthe pitch is smaller than the above range, lowering of the displayingopening rate and complication of the element producing steps occur.

[0874] If the arrangement pitch is small, and further is uniform, theorientation regulating region causes light diffraction so that thediffracted light lowers the visibility when observed as the displayelement. For avoiding the above phenomenon, it is effective to changeappropriately (e.g., randomly) the arrangement pitch in the liquidcrystal element.

[0875] The orientation regulating regions may have linear form in onedirection within the element, but may change the direction in theelement such as a dogleg form having a bent portion as shown in FIG.41(a), whereby uniform light transmission characteristics can beachieved independently of the light incident direction. As shown in FIG.41(b), the portions applying the regulating force may be arranged in thedirections, which change periodically.

[0876] In general, matrix pixels (group of pixels arranged in rows andcolumns) are formed for producing the liquid crystal display element. Inthis case, as shown in FIG. 41(c), it is desired that the arrangementdirection b of the structures providing the above regulating force isdifferent from the pixel arrangement direction a even if a straightform, or a dogleg form or the like having a bent portion is selected.

[0877] The arrangement pitch and form of the orientation regulatingregions, i.e., the projected structures, grooves on the electrode,grooves on the insulating film, the regions having the differentorientation regulating force can be freely changed by changing the maskor form plate. The orientation regulating portions may be formed oneither or both of the substrates.

[0878] (Multilayer Liquid Crystal Display Element, see FIGS. 42-45)

[0879] The effect of reducing the light scattering is achieved byregularly orientating the helical axes of the liquid crystal moleculesin the focal conic state, as already described, and this effect appearsnot only in the element of the single layer, but in the multilayerelement formed of a plurality of elements. In the multilayer element,the incident light is scattered by the first layer of the liquidcrystal, and the straight component and the scattered component enterthe second layer so that the scattering component further increases.Accordingly, the orientation regulation region for regularly orientatingthe helical axes of the liquid crystal may be arranged on at least thefirst element nearest the observation side, whereby the characteristicsof the multilayer element can be improved.

[0880] (1) Element for Full-Color Display (see FIGS. 42 and 43)

[0881] As the multilayer element of the above type, the full-colorliquid crystal display element of the reflection type can be achieved,in which the liquid crystal compositions, exhibiting a cholesteric phasein the room temperature and having the positive dielectric anisotropy,are used, and the liquid crystal materials having the selectivereflection wavelengths, which are adjusted to for red, green and blue,are used in the elements, respectively.

[0882] A multilayer element 2 00 shown in FIG. 42 includes liquidcrystal elements 50, 51 and 52 for display in blue, green and red, whichare arranged in this order from the observation side, and are stackedtogether, as well as a light absorber layer 30 on the rear-end surface.Each element has a basic structure similar to that shown in FIG. 30(a),but contains the liquid crystal composition, which is different in theselective reflection wavelength from the others. The element 50 uses theliquid crystal composition 24 a having a peak wavelength of selectivereflection in the blue region. The element 51 uses the liquid crystalcomposition 24 b having a peak wavelength of selective reflection in thegreen region. The element 52 uses the liquid crystal composition 24 chaving a peak wavelength of selective reflection in the red region. Thediameter of the spacer in each element may be appropriately determinedindependently of the others.

[0883] The layering or stacking order of these elements are notparticularly restricted. In view of the selective reflectioncharacteristics of the cholesteric liquid crystal, the blue, green andred elements may be layered in this order from the observation side,whereby the display characteristics such as brightness and color purityin the planar state can be improved.

[0884] The respective elements are bonded together by adhesive layer 23.For bonding the elements, for example, drops of the adhesive agent areapplied between the elements, and alignment is performed to preventshifting of the positions of the pixels. In this case, the adhesive maybe a setting resin material such as a thermosetting resin material or aphotosetting resin material, or may be thermoplastic resin. Therespective elements may be bonded together by the adhesive or adhesivesheet. The neighboring liquid crystal layers may use a common substrate.

[0885] In the multilayer element 200 shown in FIG. 42, the projectedstructures 13′, which are the regulating means for reducing the lightscattering in the focal conic state, are provided for each element. Inparticular, the arrangement pitch, height and material thereof areoptimized for each element, whereby the display characteristics arefurther improved.

[0886] As shown in FIG. 43, the projected structures 13′ may be arrangedon only the element 50 on the observation side.

[0887] The groove(s) formed on the transparent electrode, the groove(s)formed on the insulating film and the region(s) on the orientation filmproviding the different orientation regulating force may be employed inall the elements or only one or some (particularly, the element on theobservation side) of the elements.

[0888] (2) High Reflectance Element (see FIGS. 44 and 45)

[0889] A multilayer element 300 shown in FIG. 44 includes two liquidcrystal elements 53 and 54, which are stacked together and containsliquid crystal compositions 24d and 24 e having different opticalrotation directions, respectively. In general, when the cholestericliquid crystal is in the planar state, the light coming in the directionparallel to the helical axes of the liquid crystal molecules is dividedinto two types of (i.e., right and left) circularly polarized light. Oneof them passes through the liquid crystal layer, and the other isreflected by the liquid crystal molecules. Accordingly, by stacking theplurality of elements providing different optical rotation directions,respectively, the light utilizing efficiency can be increased. If theelements 53 and 54 have the substantially same helical pitch, thereflectance can be substantially two times larger than that of theelement providing only single optical rotation direction.

[0890] As shown in FIG. 45, a multilayer element 301 may include a{fraction (1/2)} wavelength plate 29 interposed between the neighboringliquid crystal elements 53 of the same properties. Thereby, the lightutilizing efficiency can be increased similarly to the multilayerelement 300, and the element can have high reflectance.

[0891] In any one of the above cases, at least one of the liquid crystalelements may be provided with the orientation regulating means forregularly orientating the helical axes of the liquid crystal moleculesin the focal conic state within a plane substantially parallel to thesubstrate surface. Thereby, the multilayer element can exhibit extremelyhigh contrast.

[0892] The various forms have been described, the element is notrestricted to them, and maybe modified in various manners. Variousmanners may also be employed for orientation regulation or restriction.

Experimental Examples

[0893] Experimental examples will now be described. The following kindsof material, numeric values and others are described merely by way ofexample, the element according to the invention is not restricted to thefollowing experimental examples.

Experimental Example 1′

[0894] In this experimental example, projected structures were formed.

[0895] Two glass substrates with ITO (manufactured by Central Glass Co.,Ltd.) were used. Photolithography was effected on the ITO of eachsubstrate to pattern it into belt-like forms having an electrode widthof 300 μm and a pitch of 350 μm. Then, the projected structures wereformed on the ITO-coated surface of one of the substrates in thefollowing manner.

[0896] First, positive resist PC403 (manufacture by JSR Corp.) wasapplied by spin coating on the ITO-coated surface of the substrate underthe conditions of 2000 rpm and 30 seconds, and was pre-baked at 90° C.for 2 minutes in a clean oven.

[0897] Using a photomask, which is provided with belt-like openings of 4μm in width at a pitch of 10 μm, exposure was then performed at 100mJ/cm² by a UV exposing device. Then, development was performed withdeveloper liquid (a 0.2% diluted liquid of PD-523AD manufactured by JSRCorp.) for 90 seconds, and rising was performed with flowing ultrapurewater for removing unnecessary portions. Thereby, the belt-likestructures of 1.5 μm in height were formed.

[0898] Thereafter, the structures were subjected to post-exposure by theUV exposing device at 300 mJ/cm². Post baking at 150° for five minuteswas performed by a suction hot plate so that an inclined portion wasformed on each of the above structures. Finally, a main curingprocessing was performed by a clean oven at 150° C. for 120 minutes sothat the projected structures having a trapezoidal section were formed.The projected structure had a height of about 1.5 μm, an upper surfacewidth of about 4 μm and a lower portion width of about 8 μm, and eachinclined portion thereof is about 2 μm in width.

[0899] Then, the insulating films were formed on the opposite substratesin the following manner. Polysilazane solution L120 (manufactured byTonen Corp.) was used, and a thin film thereof having a thickness of1000 Å was formed on the electrode surface of each substrate by a spincoat method. The film was heated in a constant temperature oven at 120°C. for 2 hours, and further, was heated in the constant temperature ovenat a temperature of 90° C. and a humidity of 85% for 3 hours.Thereafter, a polyimide material AL-8044 (manufactured by JSR Corp.) wasapplied by flexo printing, and was preliminarily baked at 80° C. for twominutes. Further, baking was performed at 160° C. for 60 minutes so thatthe orientation control film was formed.

[0900] Spacers (Micropearl SP2050 manufactured by Sekisui Chemical Co.,Ltd.) of 5 μm were dispersed on the substrate provided with theprojected structures, and a seal agent (XN21S manufactured by MitsuiChemicals Co., Ltd.) was applied to the other substrate while leavingthe liquid crystal inlet. These substrates were bonded together to forman empty cell.

[0901] As the liquid crystal composition, such chiral nematic liquidcrystal was used that was formed of nematic liquid crystal E31-LVmanufactured by Merk & Co. and chiral agent S-811 (24.5 wt %)manufactured by Merk & Co., and had the selective reflection peakwavelength λ adjusted to 550 nm. The liquid crystal composition had thehelical pitch of about 343 nm. The liquid crystal composition wassupplied into the cell by a vacuum-supply method. Finally, the liquidcrystal inlet was closed by a seal agent to complete the liquid crystallight modulation element.

[0902] The liquid crystal light modulation element thus prepared was setto the focal conic state by applying a voltage across the transparentelectrodes on the upper and lower substrates, and then thecharacteristics of the element were evaluated. The evaluation was madewith a spectrophotometer (Hitachi Ltd.) by measuring the transmittance(transmissivity) while keep a space from an integrating sphere.

[0903] The transmittance of the element thus measured was 78%. Forcomparison, a liquid crystal display element was prepared in the samemanner as the above except for that the projected structure was notemployed. This element had the transmittance of about 62%. Fordetermining the difference in states of the domains caused by presentand absence of the projected structures, the elements in the focal conicstate were observed with the polarization microscope. It was found thatthe directions of the helical axes were regulated and orientateduniformly in the element of this experimental example provided with theprojected structures. In contrast to this, it was observed in theelement for comparison not provided with the projected structure thatthe respective domains were oriented to have the helical axes in randomdirections.

[0904] The height, width and arrangement pitch of the projectedstructures were changed to various values for determining the influenceby them. Such a tendency was found that the excessively large or smallvalues outside the foregoing ranges lower the transmittance.

[0905] The arrangement pitch state of the projected structures waschanged between the uniform pitch state and random pitch state fordetermining the influence by it. The transmittance was not changedsubstantially. However, the uniform pitch produced the diffracted lightat a specific angle, which tendeds to lower the visibility.

[0906] Further, the arrangement direction of the projected structuresand the arrangement direction of the pixels were changes variously fordetermining the influence by them. The transmittance was substantiallysame in any case. However, there was a tendency that the moiredeteriorated the display quality if both kinds of directions were same.

[0907] Further, the longitudinal form of the projected structure waschanged between the straight form and the dogleg form for determiningthe influence by it. The transmittance was substantially same in anycase. However, the projected structure of the straight form was likelyto cause a difference in visibility between observation in the samedirection as the arrangement direction of the projected structures andobservation in the direction perpendicular thereto.

Experimental Example 2′

[0908] In this experimental example, grooves were formed on thetransparent electrode.

[0909] Two glass substrates with ITO (manufactured by Central Glass Co.,Ltd.) were used. Photolithography was effected on the ITO of eachsubstrate to pattern it into belt-like forms having an electrode widthof 300 μm and a pitch of 350 μm. Simultaneously with the patterning ofITO, the grooves were formed on one of the substrates in the followingmanner.

[0910] First, positive resist OFPR-800 (manufactured by Tokyo Ohka KogyoCo., Ltd.) was applied by spin coating on the ITO-coated surface of thesubstrate, and was pre-baked at 80° C. for 15 minutes in a clean oven.Using a photomask, which is provided with belt-like openings of 4 μm inwidth at a pitch of 10 μm, exposure was then performed at 30 mJ/cm² by aUV exposing device.

[0911] Then, development was performed with developer liquid (SD-1manufactured by Tokuyama Corp.), and rising was performed with flowingultrapure water for removing unnecessary portions. Thereafter,post-baking was performed at 120° C. for 15 minutes. Etching for ITO wasperformed with iron-salt liquid D (manufactured by Hayashi Pure ChemicalInd., Ltd.) for 20 minutes. Finally, the resist peeling processing wasperformed with a 2% water solution of NaOH for 2 minutes. In thismanner, the ITO pattern provided with the grooves was formed on one ofthe substrates. Thereafter, processing similar to that of theexperimental example 1′ was performed to form the insulating film andthe orientation film, disperse the spacers, apply the seal agent, bondthe substrates and supply the liquid crystal so that the liquid crystallight modulation element was produced.

[0912] The liquid crystal light modulation element thus prepared was setto the focal conic state by applying a voltage, and then thecharacteristics of the element were evaluated similarly to theexperimental example 1′. The transmittance of the element was 82%.

[0913] The width and arrangement pitch of the grooves were changed tovarious values for determining the influence by them. Such a tendencywas found that the excessively large or small values outside theforegoing ranges lower the transmittance.

[0914] The arrangement pitch state of the grooves was changed betweenthe uniform pitch state and random pitch state for determining theinfluence by it. The transmittance was substantially same in any case.However, the uniform pitch produced the diffracted light at a specificangle, which tended to lower the visibility.

[0915] Further, the arrangement direction of the grooves and thearrangement direction of the pixels were changes variously fordetermining the influence by them. The transmittance was substantiallysame in any case. However, there was a tendency that the moiredeteriorated the display quality if both kinds of directions weresubstantially same.

[0916] Further, the longitudinal form of the groove was changed betweenthe straight form and the dogleg form for determining the influence byit. The transmittance was substantially same in any case. However, thegroove of the straight form was likely to cause a difference invisibility between observation in the same direction as the arrangementdirection of the grooves and observation in the direction perpendicularthereto.

Experimental Example 3′

[0917] In this experimental example, rubbing processing is effected onthe orientation film.

[0918] Two glass substrates with ITO (manufactured by Central Glass Co.,Ltd.) were used. Photolithography was effected on the ITO of eachsubstrate to pattern it into belt-like forms having an electrode widthof 300 μm and a pitch of 350 μm.

[0919] An insulating material was applied to the ITO-coated surface, andwas baked to form the insulating film. A polyimide material AL-8044(manufactured by JSR Corp.) was applied by flexo printing, and waspreliminarily baked at 80° C. for two minutes. Further, baking wasperformed at 160° C. for 60 minutes so that the orientation control filmwas formed.

[0920] Then, positive resist OFPR-800 (manufactured by Tokyo Ohka KogyoCo., Ltd.) was applied by spin coating on the orientation controlfilm-coated surface of one of the substrates, and was pre-baked at 80°C. for 15 minutes in a clean oven. Using a photomask, which is similarto that used in the experimental example 1′ and is provided withopenings, exposure was then performed at 30 mJ/cm² by a UV exposingdevice. Then, development was performed with developer liquid (SD-1manufactured by Tokuyama Corp.), and rising was performed with flowingultrapure water for removing unnecessary portions. Thereafter,post-baking was performed at 120° C. for 15 minutes. In this manner, themask layer was formed for the next rubbing processing.

[0921] Then, rubbing processing was effected on the substrate coatedwith the mask layer. The rubbing processing was effected two timesthrough the mask layer with a brush roll having a pressed brush height(brush pressed amount) of 0.4 mm and a roller radius of 75 mm under theconditions of the roller rotation speed of 900 rpm and the substratemoving speed of 30 mm/sec.

[0922] After the rubbing, the resist peeling was performed withisopropyl alcohol (IPA) for two minutes to remove the mask layer.Thereafter, processing similar to that of the experimental example 1′was performed to disperse the spacers, apply the seal agent, bond thesubstrates and supply the liquid crystal so that the liquid crystallight modulation element was produced.

[0923] The liquid crystal light modulation element thus prepared was setto the focal conic state by applying a voltage, and then thecharacteristics of the element were evaluated similarly to theexperimental example 1′. The transmittance of the element was 80%.

[0924] The width and arrangement pitch of the rubbed portions werechanged to various values for determining the influence by them. Such atendency was found that the excessively large or small values outsidethe foregoing ranges lower the transmittance.

[0925] The arrangement pitch state of the rubbed portions was changedbetween the uniform pitch state and random pitch state for determiningthe influence by it. The transmittance was substantially same in anycase. However, the uniform pitch produced the diffracted light at aspecific angle, which tended to lower the visibility.

[0926] Further, the arrangement direction of the rubbed portions and thearrangement direction of the pixels were changes variously fordetermining the influence by them. The transmittance was substantiallysame in any case. However, there was a tendency that the moiredeteriorated the display quality if both kinds of directions weresubstantially same.

[0927] Further, the form of the rubbed portion was changed between thestraight form and the dogleg form for determining the influence by it.The transmittance was substantially same in any case. However, therubbed portion of the straight form was likely to cause a difference invisibility between observation in the same direction as the arrangementdirection of the rubbed portions and observation in the directionperpendicular thereto.

Experimental Example 4′

[0928] In this experimental example, optical orientation processing iseffected on the orientation film.

[0929] Two glass substrates with ITO (manufactured by Central Glass Co.,Ltd.) were used. Photolithography was effected on the ITO of eachsubstrate to pattern it into belt-like forms having an electrode widthof 300 μm and a pitch of 350 μm. Polysilazane solution L120(manufactured by Tonen Corp.) was used, and a thin film thereof having athickness of 1000 Å was formed on the electrode surface of eachsubstrate by a spin coat method. The film was heated in a constanttemperature oven at 120° C. for 2 hours, and further, was heated in theconstant temperature oven at a temperature of 90° C. and a humidity of85% for 3 hours. Thereafter, a polyimide material (TT-054 manufacturedby Hitachi Chemical Co., Ltd.) was applied by spin coating under theconditions of 300 rpm and 30 seconds, and was preliminarily baked at100° C. for one minute. Further, baking at 230° C. for 30 minutes wasperformed to complete the orientation film.

[0930] The orientation film on one of the substrates was subjected tothe partial orientation processing, which was effected through aphotomask provided with opening portions similar to that of theexperimental example 1′ and a polarizing plate by the UV irradiationdevice with 5 J/cm² and the incident angle of 15°.

[0931] Thereafter, processing similar to that of the experimentalexample 1′ was performed to disperse the spacers, apply the seal agent,bond the substrates and supply the liquid crystal so that the liquidcrystal light modulation element was produced.

[0932] The liquid crystal light modulation element thus prepared was setto the focal conic state by applying a voltage, and then thecharacteristics of the element were evaluated similarly to theexperimental example 1′. The transmittance of the element was 80%.

[0933] In connection with the width and arrangement pitch of theoptically orientated portions, such a tendency was found that theexcessively large or small values outside the foregoing ranges lower thetransmittance. If the arrangement pitch of the optically orientatedportions was uniform, the transmittance was not changed substantially,but the visibility was likely to lower due to the influence of thediffracted light. If the arrangement direction of the opticallyorientated portions and the arrangement direction of the pixels weresame, the transmittance was not changed substantially, but there was atendency that the moire deteriorated the display quality. If thearrangement of the optically orientated portion was straight, thetransmittance was not changed substantially, but a difference was likelyto be caused in visibility between observation in the same direction asthe arrangement of the optically orientated portions and observation inthe direction perpendicular thereto.

Experimental Example 5′

[0934] In this experimental example, grooves were formed on theinsulating film.

[0935] Two glass substrates with ITO (manufactured by Central Glass Co.,Ltd.) were used. Photolithography was effected on the ITO of eachsubstrate to pattern it into belt-like forms having an electrode widthof 300 μm and a pitch of 350 μm.

[0936] Then, positive resist PC335 (manufactured by JSR Corp.) wasapplied by spin coating on the ITO-coated surface of the substrate underthe conditions 3000 rpm and 30 seconds, and was pre-baked at 90° C. for2 minutes in a clean oven. Using a photomask provided with openings of 2μm in width and 10 μm in arrangement pitch, exposure was then performedat 100 mJ/cm² by a UV exposing device.

[0937] Then, development was performed with developer liquid (five timesdiluted liquid of PD-532AD manufactured by JSR Corp.), and rising wasperformed with flowing ultrapure water for removing unnecessaryportions. Thereafter, post-exposure was performed at 300 mJ/cm² by a UVexposing device. Finally, a main curing processing was performed by aclean oven at 150° C. for 120 minutes so that the insulating film of 0.5μm in height having the belt-like grooves was formed.

[0938] Thereafter, processing similar to that of the experimentalexample 1′ was performed to form the orientation film, disperse thespacers, apply the seal agent, bond the substrates and supply the liquidcrystal so that the liquid crystal light modulation element wasproduced.

[0939] The liquid crystal light modulation element thus prepared was setto the focal conic state by applying a voltage, and then thecharacteristics of the element were evaluated similarly to theexperimental example 1′. The transmittance of the element was 80%.

[0940] The width and arrangement pitch of the grooves were changed tovarious values for determining the influence by them. Such a tendencywas found that the excessively large or small values outside theforegoing ranges lower the transmittance.

[0941] The arrangement pitch of the grooves was changed between theuniform pitch and random pitch for determining the influence by it. Thetransmittance was not changed substantially. However, the uniform pitchproduced the diffracted light at a specific angle, which tended to lowerthe visibility.

[0942] Further, the arrangement direction of the grooves and thearrangement direction of the pixels were changes variously fordetermining the influence by them. The transmittance was substantiallysame in any case. However, there was a tendency that the moiredeteriorated the display quality if both kinds of directions were same.

[0943] Further, the longitudinal form of the groove was changed betweenthe straight form and the dogleg form for determining the influence byit. The transmittance was substantially same in any case. However, thegroove of the straight form was likely to cause a difference invisibility between observation in the same direction as the arrangementdirection of the grooves and observation in the direction perpendicularthereto.

Experimental Example 6′

[0944] In this experimental example, projected structures were formed inthe multilayer liquid crystal display element.

[0945] As substrates, two films FST-5352 (manufactured by SumitomoBakelite Co., Ltd.) with flexible ITO film were used. Photolithographywas effected on the ITO of each substrate to pattern it into belt-likeforms having an electrode width of 300 μm and a pitch of 350 μm.

[0946] On the surface of one (first substrate) of the substratesprovided with the transparent electrode, the projected structures havinga trapezoidal section was formed similarly to the experimental example1′. The projected structure had a height of about 1.5 μm, an uppersurface width of about 4 μm and an inclined side portion width of about2 μm.

[0947] Polysilazane solution L120 (manufactured by Tonen Corp.) wasused, and a thin film thereof having a thickness of 1000 Å was formed onthe electrode surface of each substrate by a spin coat method. The filmwas heated in a constant temperature oven at 120° C. for 2 hours, andfurther, was heated in the constant temperature oven at a temperature of90° C. and a humidity of 85% for 3 hours. Thus the insulating film wasprepared. Then, an orientation film material AL4552 (manufactured by JSRCorp.) was applied by the spin coat method to form a thin film of 500Åin thickness on the insulating film of each substrate, and was heated inthe constant temperature oven at a temperature of 165° C. for 2 hours.Thus the orientation film was prepared on which the rubbing processingwas not performed.

[0948] UV-curing resin (epoxy resin) material UV RESIN T-470/UR-7092(manufactured by Nagase-CIBA Ltd., glass transition point of 144° C.),in which spacers (Micropearl SP205) of 5 μm in particle diameter weremixed, was applied to the periphery of the first substrate by screenprinting. Then, the resin material was irradiated with light emittedfrom a high-voltage mercury lamp HMW-244-11CM (manufactured by ORCProducing Co., Ltd.) of 4 kW with an integrated amount of light of 4000mJ/cm². Thereby, a seal was formed. The seal thus formed had an annularform surrounding the display region. After applying the resin materialfor the seal, it was sucked and fixed on the hot plate at 80° C. for 30minutes.

[0949] Then, resin structures for adhering the opposite substrates wereformed on the substrate (second substrate) not provided with theprojected structures. In this example, polyester resin AlonmeltPES-360SA40 (manufactured by Three Bond Co., Ltd), which isthermoplastic resin, was used for the above resin structures, and wasapplied by the screen printing method to form the resin structuresarranged in a grid-like form with a pitch of 350 μm. Each resinstructure had a diameter of 50 μm and a height of 6,5 μm.

[0950] In this manner, the two substrates were prepared before bonding.The first substrate was vacuum-sucked onto the hot plate, and liquidcrystal composition containing spacers of an intended particle diameterdispersed therein was applied to the end of the substrate. The oppositesubstrates were overlaid at the end carrying the resin composition suchthat the belt-like electrodes on the opposite substrates may beperpendicular to each other. The substrates were pressed and bondedtogether by a heating roller and a pressure roller.

[0951] In the bonding operation, the first substrate was vacuum-suckedand fixed onto the hot plate preheated to 80° C. with its orientationfilm directed upward, and the liquid crystal composition was applied tothe end of the substrate. The volume of applied composition is smallerthan a volume of a space defined between the opposite substrates andwithin the seal.

[0952] The liquid crystal composition was formed of nematic liquidcrystal E44 and chiral agent S811 (32 wt %) both manufactured by Merk &Co., and contained spacers formed of Micropearl SP205 of 5 μm inparticle diameter. A liquid crystal element for blue display wasprepared in this manner, In this element, the liquid crystal layer hadthe selective reflection wavelength of 490 nm, and the liquid crystalcomposition had the helical pitch of about 306 nm.

[0953] In similar manners, the liquid crystal elements for green displayand red display were prepared. The liquid crystal composition for greendisplay was formed of nematic liquid crystal E44 and 30 wt % of chiralagent S811, both manufactured by Merk & Co. The liquid crystalcomposition for red display was formed of nematic liquid crystal E44 and25 wt % of chiral agent S811, both manufactured by Merk & Co. Forproviding the substrate gaps of 7 μm and 9 μm, spacers SP205 and SP209(manufactured by Sekisui Chemical Co., Ltd.) of 7 μm and 9 μm indiameter were used. The liquid crystal element for green display had theselective reflection wavelength of 560 nm, and the liquid crystalelement for red display had the selective reflection wavelength of 680nm. The helical pitches of the liquid crystal composition were about 350nm and about 425 nm.

[0954] After forming the elements for display in respective colors, therespective elements were bonded together by an adhesive T-#5511(manufactured by Sekisui Chemical Co., Ltd.) while locating the pixelsin the aligned positions. A light absorber layer was arranged on thesubstrate surface in the third layer not provided with the transparentelectrode. Thereby, the multilayer liquid crystal display element wasprepared.

[0955] Predetermined voltages were applied to the respective elements ofthe multilayer liquid crystal display element thus prepared to set allthe liquid crystal layer to the focal conic state, and the Y-value of3.5 was obtained when measured by a reflective spectrocolorimeterCM-3700d (manufactured by Minolta Co., Ltd.). If the projected structurewas not present, the Y-value was equal to 4.5.

Experimental Example 7′

[0956] In this experimental example, projected structures were formed inthe two elements of the multilayer liquid crystal display element.

[0957] In addition to the liquid crystal display element for bluedisplay, the projected structures having a trapezoidal section wereformed in the liquid crystal display element for green display,similarly to the experimental example 6′. The arrangement pitch of thestructure was 14 μm. The projected structure had a height of about 1.5μm, an upper surface width of about 4 μm and an inclined portion widthof about 2 μm. Structures and manners other than the above are the sameas those of the experimental example 6′.

[0958] Predetermined voltages were applied to the respective elements ofthe multilayer liquid crystal display element thus prepared to set allthe liquid crystal layer to the focal conic state, and the Y-value of3.1 was obtained when measured by the reflective spectrocolorimeterCM-3700d (manufactured by Minolta Co., Ltd.).

Experimental Example 8′

[0959] In this experimental example, projected structures were formed inthe three elements of the multilayer liquid crystal display element.

[0960] In addition to the liquid crystal display elements for bluedisplay and green display, the projected structures were formed with apitch of 18 μm in the liquid crystal display element for red display.The projected structure had a height of about 1.5 μm, an upper surfacewidth of about 4 μm and an inclined portion width of about 2 μm.Structures and manners other than the above are the same as those of theexperimental example 6′.

[0961] Predetermined voltages were applied to the respective elements ofthe multilayer liquid crystal display element thus prepared to set allthe liquid crystal layer to the focal conic state, and the Y-value of2.8 was obtained when measured by the reflective spectrophotometriccalorimeter CM-3700d (manufactured by Minolta Co., Ltd.).

Experimental Example 9′

[0962] In this experimental example, grooves were formed on thetransparent electrode in the multilayer liquid crystal display element.

[0963] The liquid crystal display element for green display was formedin a manner similar to that of the experimental example 5′ except forthat grooves of a pitch of 10 μm and a width of 3.0 μm were formed onthe transparent electrode of the substrate remote from the observationside of the green display liquid crystal display element, and theprojected structure was not formed. The grooves were formed in a mannersimilar to that of the experimental example 2′.

[0964] The liquid crystal display elements for blue display and greendisplay were prepared in a manner similar to that of the experimentalexample 5′ without forming the projected structure and the groove on thetransparent electrode. Thus, the multilayer liquid crystal displayelement was formed.

[0965] Predetermined voltages were applied to the respective elements ofthe multilayer liquid crystal display element thus prepared to set allthe liquid crystal layer to the focal conic state, and the Y-value of3.4 was obtained when measured by the reflective spectrocolorimeterCM-3700d (manufactured by Minolta Co., Ltd.).

Experimental Example 10′

[0966] In this experimental example, projected structures were formed onthe three elements in the multilayer liquid crystal display element withdifferent sizes and arrangement pitches depending on the elements,respectively.

[0967] The multilayer liquid crystal element was prepared in a mannersimilar to that of the experimental example 7′ except for that differentmasks were used for forming the projected structures of different sizesand arrangement pitches depending on the elements, respectively. Theliquid crystal display element for blue display had the projectedstructures of the pitch of 10 μm and height of 3.0 μm. The liquidcrystal display element for green display had the projected structuresof the pitch of 14 μm and height of 3.5 μm. The liquid crystal displayelement for red display had the projected structures of the pitch of 18μm and width of 4.5 μm.

[0968] Predetermined voltages were applied to the respective elements ofthe multilayer liquid crystal display element thus prepared to set allthe liquid crystal layer to the focal conic state, and the Y-value of2.8 was obtained when measured by the reflective spectrocolorimeterCM-3700d (manufactured by Minolta Co., Ltd.).

Experimental Example 11′

[0969] In this experimental example, a structure formed of two layers ofcells having the same selective wavelength and different helicaldirections were prepared.

[0970] The left handed rotatory chiral nematic liquid crystal was formedof nematic liquid crystal E-31LV and 24.5 wt % of chiral agent S-811,both manufactured by Merk & Co. The right handed rotatory chiral nematicliquid crystal was formed of nematic liquid crystal E-31LV and 24.5 wt %of chiral agent R-811, both manufactured by Merk & Co.

[0971] These liquid crystal compositions had the selective reflectionwavelength of 550 nm for green display. These liquid crystalcompositions had the helical pitch of 343 nm.

[0972] In the producing method similar to that of the experimentalexample 1′ and with the similar projected structures, the respectiveelements were prepared. The elements thus prepared were stacked withtransparent adhesive layers therebetween so that the element wasprepared. The element thus prepared had the reflectance of 73% in thereflecting state and the reflectance of 2% in the transparent state, andtherefore had high contrast.

[0973] Although the present invention has been described and illustratedin detail, it is clearly understood that the same is by way ofillustration and example only and is not to be taken by way oflimitation, the spirit and scope of the present invention being limitedonly by the terms of the appended claims.

What is claimed is:
 1. A liquid crystal display element comprising aliquid crystal layer including liquid crystal contained between a pairof substrates and exhibiting a cholesteric phase, wherein an orientationfilm is arranged on at least one of said paired substrates, and is incontact with said liquid crystal layer, and liquid crystal molecularorientation processing for portions of each orientation filmcorresponding to pixel regions is effected in a manner different fromthat effected on at least a portion of a portion corresponding tonon-pixel region of the orientation film on at least one of thesubstrates.
 2. A liquid crystal display element according to claim 1,wherein said orientation film arranged on at least one of saidsubstrates is configured such that the liquid crystal molecularorientation processing is effected on the portions corresponding to thepixel regions and at least a portion of the portion corresponding to thenon-pixel region in different manners, respectively.
 3. A liquid crystaldisplay element according to claim 1, wherein said orientation film isarranged on each of the substrates.
 4. A liquid crystal display elementaccording to claim 3, wherein said orientation film arranged on each ofsaid substrates is configured such that the liquid crystal molecularorientation processing is effected on the portions corresponding to thepixel regions and at least a portion of the portion corresponding to thenon-pixel region in different manners, respectively.
 5. A liquid crystaldisplay element according to claim 1, wherein said orientation filmhaving the portion corresponding to said non-pixel region and subjectedto the orientation processing is configured such that said orientationprocessing is not effected on the portions corresponding to the pixelregions of said orientation film, and the orientation processing iseffected on at least a portion of the portion corresponding to thenon-pixel region.
 6. A liquid crystal display element comprising aliquid crystal layer arranged between a pair of substrates and includingliquid crystal exhibiting a cholesteric phase, and a plurality ofpixels, wherein an orientation film is formed on at least one of thesubstrates, and liquid crystal molecular orientation processing iseffected on at least a portion of a portion corresponding to non-pixelregion of the orientation film.
 7. A liquid crystal display elementaccording to claim 1, wherein the orientation processing effected on atleast a portion of the portion corresponding to the non-pixel region ofsaid orientation film is performed to set the liquid crystal of thenon-pixel region corresponding to the orientation-processed portion to aplanar state.
 8. A liquid crystal display element formed of a pluralityof liquid crystal layers stacked together and each held between a pairof substrates, wherein at least one of said plurality of liquid crystallayers is provided with an orientation film arranged on at least one ofpaired substrates holding the liquid crystal layer therebetween andbeing in contact with the liquid crystal layer, and liquid crystalmolecular orientation processing for portions of each orientation filmcorresponding to pixel regions is effected in a manner different fromthat effected on at least a portion of a portion corresponding tonon-pixel region of the orientation film on at least one of thesubstrates.
 9. A liquid crystal display element according to claim 8,wherein said orientation film is employed for each of said liquidcrystal layers and is arranged on at least one of the paired substratesholding the liquid crystal layer therebetween, and liquid crystalmolecular orientation processing is effected on the orientation film foreach of the liquid crystal layers such that said processing is effectedon the portions corresponding to the pixel regions in a manner differentfrom that effected on at least a portion of the portion corresponding tothe non-pixel region of the orientation film on at least one of thesubstrates.
 10. A liquid crystal display element according to claim 8,wherein said orientation film arranged on at least one of said pairedsubstrates holding the liquid crystal layer is configured such that theliquid crystal molecular orientation processing is effected on theportions corresponding to the pixel regions and at least a portion ofthe portion corresponding to the non-pixel region in different manners,respectively.
 11. A liquid crystal display element according to claim 8,wherein said orientation film is arranged on each of surfaces of thesubstrates opposed to each of the liquid crystal layers.
 12. A liquidcrystal display element according to claim 1, wherein said orientationprocessing of the orientation film is effected by rubbing processing.13. A liquid crystal display element according to claim 6, wherein saidorientation processing of the orientation film is effected by rubbingprocessing.
 14. A liquid crystal display element according to claim 8,wherein said orientation processing of the orientation film is effectedby rubbing processing.
 15. A liquid crystal display element according toclaim 1, wherein said orientation processing of the orientation film iseffected by optical orientation processing.
 16. A liquid crystal displayelement according to claim 6, wherein said orientation processing of theorientation film is effected by optical orientation processing.
 17. Aliquid crystal display element according to claim 8, wherein saidorientation processing of the orientation film is effected by opticalorientation processing.
 18. A liquid crystal light modulation elementcomprising a liquid crystal layer held between a pair of substrates andincluding a liquid crystal material exhibiting a cholesteric phase andhaving a peak of a selective reflection wavelength in a visiblewavelength range, wherein said liquid crystal layer in a selectivereflection state has pixel regions neighboring to the oppositesubstrates, respectively, and liquid crystal domains in the pixelregions neighboring to at least one of said substrates are in a mixedstate of a polydomain state and a monodomain state.
 19. A liquid crystallight modulation element according to claim 18, wherein, in theselective reflection state, each of said liquid crystal domains in thepixel regions near the opposite substrates is in said mixed state, and aratio between the liquid crystal domains taking the polydomain state andthe liquid crystal domains taking the monodomain state is differentbetween the liquid crystal domain in each of the pixel regions near oneof the opposite substrates and the liquid crystal domain in each of thepixel regions near the other substrate.
 20. A liquid crystal lightmodulation element according to claim 19, wherein, in the selectivereflection state, the liquid crystal domains in each of the pixelregions near the substrate on an element observation side include theliquid crystal domains taking said polydomain state at a higher ratethan that on the other side.
 21. A liquid crystal light modulationelement according to claim 18, wherein, in the selective reflectionstate, the liquid crystal domains in each of the pixel regions near oneof the opposite substrates take said mixed state and the liquid crystaldomains in each of the pixel regions near the other substrate take onlysaid polydomain state.
 22. A liquid crystal light modulation elementaccording to claim 21, wherein in the selective reflection state, theliquid crystal domains in the pixel regions near the substrate on theelement observation side take only said polydomain state.
 23. A liquidcrystal light modulation element according to claim 18, wherein anorientation control layer is arranged at least on the substrate opposedto the liquid crystal domains in said mixed state, and particularly onthe side of said substrate opposed to said liquid crystal domains, andis in contact with the liquid crystal, and the liquid crystal moleculesin said mixed state and the selective reflection state is subjected tothe orientation control by the orientation control layer.
 24. A liquidcrystal light modulation element according to claim 23, wherein saidorientation control is performed by the rubbing processing effected onthe orientation control layer arranged on the substrate opposed to theliquid crystal domains in said mixed state.
 25. A liquid crystal lightmodulation element according to claim 24, wherein said orientationcontrol layer subjected to the rubbing has a rubbing density of 10 orlower.
 26. A liquid crystal light modulation element according to claim23, wherein said orientation control is performed by emitting lightunder predetermined condition(s) to the orientation control layerarranged on the substrate opposed to the liquid crystal domains in saidmixed state.
 27. A liquid crystal light modulation element according toclaim 26, wherein said predetermined condition(s) include any one of anamount of the emitted light, a substrate temperature, an incident angleof the incident light on the substrate surface.
 28. A liquid crystallight modulation element according to claim 26, wherein said light isultraviolet light.
 29. A liquid crystal light modulation elementcomprising a liquid crystal layer held between a pair of substrates andincluding a liquid crystal material exhibiting a cholesteric phase andhaving a peak of a selective reflection wavelength in a visiblewavelength range, wherein said liquid crystal layer in a selectivereflection state has pixel regions neighboring to the oppositesubstrates, respectively, liquid crystal domains in the pixel regionstake a polydomain state, and angles of cholesteric helical axes of theliquid crystal with respect to the substrate normal are differentbetween the liquid crystal domains in the pixel regions near one of theopposite substrates and the liquid crystal domains in the pixel regionsnear the other substrate.
 30. A liquid crystal light modulation elementaccording to claim 29, wherein, in the selective reflection state, theliquid crystal in the liquid crystal domains in each of the pixelregions near the substrate on an observation side has the cholesterichelical axes defining a larger angle with respect to the substratenormal than that of the liquid crystal in the liquid crystal domainsremote from the observation side.
 31. A liquid crystal light modulationelement according to claim 29, further comprising: orientation controllayers arranged on the sides of said paired substrates opposed to saidliquid crystal layer, respectively, and being in contact with the liquidcrystal for controlling the angles of the cholesteric helical axes ofthe liquid crystal in the respective liquid crystal domains of the pixelregions near the opposite substrates with respect to the substratenormal in the selective reflection state.
 32. A liquid crystal lightmodulation element according to claim 31, wherein a difference occurs inthe angle of the cholesteric helical axis of the liquid crystal in theselective reflection state with respect to the substrate normal betweenthe liquid crystal domains in the pixel regions near one of the oppositesubstrates and the liquid crystal domains in the pixel regions near theother substrate, and said difference is caused by the fact that at leastone of the orientation control layers arranged on the oppositesubstrates is subjected to rubbing.
 33. A liquid crystal lightmodulation element according to claim 32, wherein said orientationcontrol layer subjected to the rubbing has a rubbing density of 10 orlower.
 34. A liquid crystal light modulation element according to claim31, wherein a difference occurs in the angle of the cholesteric helicalaxis of the liquid crystal in the selective reflection state withrespect to the substrate normal between the liquid crystal domains inthe pixel regions near one of the opposite substrates and the liquidcrystal domains in the pixel regions near the other substrate, and saiddifference is caused by the fact that at least one of the orientationcontrol layers, which are arranged on the opposite substrates,respectively, is irradiated with light under predetermined condition(s).35. A liquid crystal light modulation element according to claim 34,wherein said predetermined condition(s) include any one of an amount ofthe emitted light, a substrate temperature, an incident angle of theincident light on the substrate surface.
 36. A liquid crystal lightmodulation element according to claim 34, wherein said light isultraviolet light.
 37. A liquid crystal light modulation elementaccording to claim 31, wherein material parameters of the orientationcontrol layers provided for the opposite substrates are different fromeach other.
 38. A liquid crystal light modulation element according toclaim 18, wherein, in the selective reflection state, the angle of thecholesteric helical axis of the liquid crystal in each of the liquidcrystal domains of the pixel regions near the opposite substrates withrespect to the substrate normal is 20° or less.
 39. A liquid crystallight modulation element according to claim 29, wherein, in theselective reflection state, the angle of the cholesteric helical axis ofthe liquid crystal in each of the liquid crystal domains of the pixelregions near the opposite substrates with respect to the substratenormal is 20° or less.
 40. A multilayer liquid crystal light modulationelement formed of a plurality of liquid crystal layers stacked togetherand each held between a pair of substrates, wherein at least one of saidplurality of liquid crystal layers and the corresponding pair ofsubstrates holding the liquid crystal form the liquid crystal lightmodulation element according to claim
 18. 41. A multilayer liquidcrystal light modulation element formed of a plurality of liquid crystallayers stacked together and each held between a pair of substrates,wherein at least one of said plurality of liquid crystal layers and thecorresponding pair of substrates holding the liquid crystal form theliquid crystal light modulation element according to claim
 29. 42. Amultilayer liquid crystal light modulation element according to claim40, wherein, in any neighboring liquid crystal light modulationelements, an angle of the cholesteric helical axis of the liquid crystalin the liquid crystal domains of each of the pixel regions near thesubstrate on an observation side in the liquid crystal light modulationelement in the selective reflection state on the element observationside with respect to the substrate normal is larger than an angle of thecholesteric helical axis of the liquid crystal in the liquid crystaldomains of each of the pixel regions near the substrate on theobservation side in the liquid crystal light modulation element in theselective reflection state on the side opposite to the elementobservation side with respect to the substrate normal.
 43. A multilayerliquid crystal light modulation element according to claim 41, wherein,in any neighboring liquid crystal light modulation elements, the angleof the cholesteric helical axis of the liquid crystal in the liquidcrystal domains of each of the pixel regions near the substrate on anobservation side in the liquid crystal light modulation element in theselective reflection state on the element observation side with respectto the substrate normal is larger than the angle of the cholesterichelical axis of the liquid crystal in the liquid crystal domains of eachof the pixel regions near the substrate on the observation side in theliquid crystal light modulation element in the selective reflectionstate on the side opposite to the element observation side with respectto the substrate normal.
 44. A multilayer liquid crystal lightmodulation element according to claim 40, wherein, in any neighboringliquid crystal light modulation elements, an angle of the cholesterichelical axis of the liquid crystal in the liquid crystal domains of eachof the pixel regions near the substrate on a side opposite to anobservation side in the liquid crystal light modulation element in theselective reflection state on the element observation side with respectto the substrate normal is larger than an angle of the cholesterichelical axis of the liquid crystal in the liquid crystal domains of eachof the pixel regions near the substrate opposite to the observation sidein the liquid crystal light modulation element in the selectivereflection state on the side opposite to the element observation sidewith respect to the substrate normal.
 45. A multilayer liquid crystallight modulation element according to claim 41, wherein, in anyneighboring liquid crystal light modulation elements, the angle of thecholesteric helical axis of the liquid crystal in the liquid crystaldomains of each of the pixel regions near the substrate on a sideopposite to an observation side in the liquid crystal light modulationelement in the selective reflection state on the element observationside with respect to the substrate normal is larger than the angle ofthe cholesteric helical axis of the liquid crystal in the liquid crystaldomains of each of the pixel regions near the substrate opposite to theobservation side in the liquid crystal light modulation element in theselective reflection state on the side opposite to the elementobservation side with respect to the substrate normal.
 46. A multilayerliquid crystal light modulation element according to claim 42, wherein,in any neighboring liquid crystal light modulation elements, an angle ofthe cholesteric helical axis of the liquid crystal in the liquid crystaldomains of each of the pixel regions near the substrate on a sideopposite to an observation side in the liquid crystal light modulationelement in the selective reflection state on the element observationside with respect to the substrate normal is larger than an angle of thecholesteric helical axis of the liquid crystal in the liquid crystaldomains of each of the pixel regions near the substrate opposite to theobservation side in the liquid crystal light modulation element in theselective reflection state on the side opposite to the elementobservation side with respect to the substrate normal.
 47. A multilayerliquid crystal light modulation element according to claim 43, wherein,in any neighboring liquid crystal light modulation elements, the angleof the cholesteric helical axis of the liquid crystal in the liquidcrystal domains of each of the pixel regions near the substrate on aside opposite to an observation side in the liquid crystal lightmodulation element in the selective reflection state on the elementobservation side with respect to the substrate normal is larger than theangle of the cholesteric helical axis of the liquid crystal in theliquid crystal domains of each of the pixel regions near the substrateopposite to the observation side in the liquid crystal light modulationelement in the selective reflection state on the side opposite to theelement observation side with respect to the substrate normal.
 48. Amultilayer liquid crystal light modulation element formed of a pluralityof liquid crystal layers stacked together and each held between a pairof substrates, wherein at least one of said plurality of liquid crystallayers and the corresponding pair of substrates holding the liquidcrystal forms the liquid crystal light modulation element according toclaim
 24. 49. A multilayer liquid crystal light modulation elementformed of a plurality of liquid crystal layers stacked together and eachheld between a pair of substrates, wherein at least one of saidplurality of liquid crystal layers and the corresponding pair ofsubstrates holding the liquid crystal forms the liquid crystal lightmodulation element according to claim
 32. 50. A multilayer liquidcrystal light modulation element according to claim 48, wherein, in anyneighboring liquid crystal light modulation elements, an angle of thecholesteric helical axis of the liquid crystal in the liquid crystaldomains of each of the pixel regions near the substrate on anobservation side in the liquid crystal light modulation element in theselective reflection state on the element observation side with respectto the substrate normal is larger than an angle of the cholesterichelical axis of the liquid crystal in the liquid crystal domains of eachof the pixel regions near the substrate on the observation side in theliquid crystal light modulation element in the selective reflectionstate on the side opposite to the element observation side with respectto the substrate normal.
 51. A multilayer liquid crystal lightmodulation element according to claim 49, wherein, in any neighboringliquid crystal light modulation elements, the angle of the cholesterichelical axis of the liquid crystal in the liquid crystal domains of eachof the pixel regions near the substrate on an observation side in theliquid crystal light modulation element in the selective reflectionstate on the element observation side with respect to the substratenormal is larger than the angle of the cholesteric helical axis of theliquid crystal in the liquid crystal domains of each of the pixelregions near the substrate on the observation side in the liquid crystallight modulation element in the selective reflection state on the sideopposite to the element observation side with respect to the substratenormal.
 52. A multilayer liquid crystal light modulation elementaccording to claim 48, wherein, in any neighboring liquid crystal lightmodulation elements, an angle of the cholesteric helical axis of theliquid crystal in the liquid crystal domains of each of the pixelregions near the substrate on a side opposite to an observation side inthe liquid crystal light modulation element in the selective reflectionstate on the element observation side with respect to the substratenormal is larger than an angle of the cholesteric helical axis of theliquid crystal in the liquid crystal domains of each of the pixelregions near the substrate opposite to the observation side in theliquid crystal light modulation element in the selective reflectionstate on the side opposite to the element observation side with respectto the substrate normal.
 53. A multilayer liquid crystal lightmodulation element according to claim 49, wherein, in any neighboringliquid crystal light modulation elements, the angle of the cholesterichelical axis of the liquid crystal in the liquid crystal domains of eachof the pixel regions near the substrate on a side opposite to anobservation side in the liquid crystal light modulation element in theselective reflection state on the element observation side with respectto the substrate normal is larger than the angle of the cholesterichelical axis of the liquid crystal in the liquid crystal domains of eachof the pixel regions near the substrate opposite to the observation sidein the liquid crystal light modulation element in the selectivereflection state on the side opposite to the element observation sidewith respect to the substrate normal.
 54. A liquid crystal lightmodulation element according to claim 50, wherein in any neighboringliquid crystal light modulation elements, the rubbing density of theorientation control layer subjected to the rubbing and arranged in theliquid crystal light modulation element on the element observation sideis smaller than the rubbing density of the orientation control layer,corresponding to said orientation control layer, subjected to therubbing and arranged in the liquid crystal light modulation element onthe opposite side.
 55. A liquid crystal light modulation elementaccording to claim 51, wherein in any neighboring liquid crystal lightmodulation elements, the rubbing density of the orientation controllayer subjected to the rubbing and arranged in the liquid crystal lightmodulation element on the element observation side is smaller than therubbing density of the orientation control layer, corresponding to saidorientation control layer, subjected to the rubbing and arranged in theliquid crystal light modulation element on the opposite side.
 56. Amethod of producing a liquid crystal light modulation element includinga liquid crystal layer held between a pair of substrates and including aliquid crystal material exhibiting a cholesteric phase and having a peakof a selective reflection wavelength in a visible wavelength range,comprising: a substrate processing step of processing at least one ofsaid paired substrates such that said liquid crystal layer in theselective reflection state has pixel regions neighboring to the oppositesubstrates, respectively, and liquid crystal domains in the pixelregions neighboring to at least one of the substrates are in a mixedstate of a polydomain state and a monodomain state; and a step ofarranging the liquid crystal layer between the paired substratesincluding the substrate(s) subjected to said substrate processing step.57. A method of producing the liquid crystal light modulation elementaccording to claim 56, wherein said substrate processing step isperformed to process the paired substrates such that the liquid crystaldomains in the pixel regions near the substrate remote from an elementobservation side are in said mixed state, and the liquid crystal domainsin the pixel regions near the substrate on the element observation sidetake only the polydomain state in the selective refection state.
 58. Amethod of producing the liquid crystal light modulation elementaccording to claim 56, wherein said substrate processing step includes astep of providing an orientation control layer on the side opposed tothe liquid crystal domains in said mixed state of at least one of saidpaired substrates opposed to the liquid crystal domains in the mixedstate; and a rubbing processing step of effecting rubbing processing onthe orientation control layer arranged on the substrate opposed to saidliquid crystal domains in the mixed state, and said rubbing step isperformed to provide the orientation control layer rubbed at a rubbingdensity of 10 or less.
 59. A method of producing a liquid crystal lightmodulation element including a liquid crystal layer held between a pairof substrates and including a liquid crystal material exhibiting acholesteric phase and having a peak of a selective reflection wavelengthin a visible wavelength range, comprising: a substrate processing stepof processing said paired substrates such that the liquid crystal layerin the selective reflection state has pixel regions neighboring to theopposite substrates, respectively, liquid crystal domains in the pixelregions take a polydomain state, and the angles of the cholesterichelical axes of the liquid crystal with respect to the substrate normalare different between the liquid crystal domains in the pixel regionsnear one of the opposite substrates and the liquid crystal domains inthe pixel regions near the other substrate; and a step of arranging saidliquid crystal layer between said paired substrates subjected to saidsubstrate processing step.
 60. A method of producing the liquid crystallight modulation element according to claim 59, wherein said substrateprocessing step is performed such that the angle of the cholesterichelical axis of the liquid crystal in the liquid crystal domains of eachof the pixel regions near the substrate on an observation side withrespect to the substrate normal is larger than the angle of thecholesteric helical axis of the liquid crystal in the liquid crystaldomains of each of the pixel regions near the opposite substrate withrespect to the substrate normal in the selective reflection state.
 61. Amethod of producing the liquid crystal light modulation elementaccording to claim 59, wherein said substrate processing step includes astep of providing orientation control layers on the sides opposed tosaid liquid crystal layer of said paired substrate; and a rubbingprocessing step of effecting rubbing processing on at least one of theorientation control layers arranged on said opposite substrates, andsaid rubbing step is performed to provide the orientation control layerrubbed at a rubbing density of 10 or less.
 62. A liquid crystal lightmodulation element for performing light modulation by utilizing a focalconic state of liquid crystal molecules included in a liquid crystallayer held between a pair of substrates, wherein helical axes of theliquid crystal molecules in the focal conic state extend in regulardirections within plane substantially parallel to a substrate surface.63. A liquid crystal light modulation element according to claim 62,further comprising: orientation regulating means for the liquid crystalmolecules for orientating the helical axes of the liquid crystalmolecules in the focal conic state in regular directions within a planesubstantially parallel to the substrate surface.
 64. A liquid crystallight modulation element according to claim 62, wherein the helical axesof the liquid crystal molecules in the focal conic state are orientatedin regular directions when a predetermined electric field is appliedacross the substrates.
 65. A liquid crystal light modulation elementaccording to claim 64, wherein anisotropy is caused in directions oflines of electric force of said electric field for orientating thehelical axes of the liquid crystal molecules in the focal conic state inregular directions.
 66. A liquid crystal light modulation elementaccording to claim 65, wherein the anisotropy is caused in thedirections of the equal potential lines of said electric field by aprojected structure formed on at least one of said substrates.
 67. Aliquid crystal light modulation element according to claim 66, whereinsaid projected structure has a rib-like form.
 68. A liquid crystal lightmodulation element according to claim 66, wherein said projectedstructure has a side surface inclined with respect to a direction of asubstrate normal.
 69. A liquid crystal light modulation elementaccording to claim 66, wherein an electrode is formed on a surface ofeach of said substrates, and said projected structure is formed on theelectrode of at least one of the substrates.
 70. A liquid crystal lightmodulation element according to claim 66, wherein a height h of saidprojected structure and a gap d between said substrates satisfy arelationship of d/20<h<d/2.
 71. A liquid crystal light modulationelement according to claim 66, wherein a width W of said projectedstructure and a helical pitch p of the liquid crystal molecules satisfya relationship of p<W<20p.
 72. A liquid crystal light modulation elementaccording to claim 66, wherein an arrangement pitch L of said projectedstructures and a helical pitch p of the liquid crystal molecules satisfya relationship of 5p<L<100p.
 73. A liquid crystal light modulationelement according to claim 72, wherein said arrangement pitch of saidprojected structures is not uniform within a range satisfying saidrelationship.
 74. A liquid crystal light modulation element according toclaim 66, comprising: a plurality of pixels arranged in a directiondifferent from a direction of arrangement of said projected structures.75. A liquid crystal light modulation element according to claim 66,comprising: a plurality of regions which are different in a direction ofarrangement of said projected structures.
 76. A liquid crystal lightmodulation element according to claim 65, wherein an electrode is formedon each of said substrates, and the anisotropy is caused in thedirections of the lines of electric force of said electric field by agroove formed on the electrode on at least one of said substrates.
 77. Aliquid crystal light modulation element according to claim 76, wherein awidth W of said groove and a helical pitch p of the liquid crystalmolecules satisfy a relationship of p<W<20p.
 78. A liquid crystal lightmodulation element according to claim 76, wherein an arrangement pitch Lof said grooves and a helical pitch p of the liquid crystal moleculessatisfy a relationship of 5p<L<100p.
 79. A liquid crystal lightmodulation element according to claim 78, wherein said arrangement pitchL of said grooves is not uniform within a range satisfying saidrelationship.
 80. A liquid crystal light modulation element according toclaim 76, comprising: a plurality of pixels arranged in a directiondifferent from a direction of arrangement of said grooves.
 81. A liquidcrystal light modulation element according to claim 76, comprising: aplurality of regions which are different in a direction of arrangementof said grooves.
 82. A liquid crystal light modulation element accordingto claim 65, wherein an insulating film is formed on at least one of thesubstrates, and the anisotropy is caused in the directions of the linesof electric force of said electric field by a groove formed on saidinsulating film.
 83. A liquid crystal light modulation element accordingto claim 82, wherein a width W of said groove and a helical pitch p ofthe liquid crystal molecules satisfy a relationship of p<W<20p.
 84. Aliquid crystal light modulation element according to claim 82, whereinan arrangement pitch L of said grooves and a helical pitch p of theliquid crystal molecules satisfy a relationship of 5p<L<100p.
 85. Aliquid crystal light modulation element according to claim 84, whereinsaid arrangement pitch L of said grooves is not uniform within a rangesatisfying said relationship.
 86. A liquid crystal light modulationelement according to claim 62, wherein a region providing a differentorientation regulating force is arranged partially on a surface of atleast one of the substrates in contact with the liquid crystal fororientating helical axes of the liquid crystal molecules in regulardirections.
 87. A liquid crystal light modulation element according toclaim 86, wherein an orientation film is arranged on the surface, incontact with the liquid crystal, of the substrate provided with saidregion.
 88. A liquid crystal light modulation element according to claim86, wherein said region is formed by partially effecting rubbing.
 89. Aliquid crystal light modulation element according to claim 87, whereinsaid region is formed by partially effecting rubbing.
 90. A liquidcrystal light modulation element according to claim 86, wherein saidregion is formed by partially effecting light irradiation.
 91. A liquidcrystal light modulation element according to claim 87, wherein saidregion is formed by partially effecting light irradiation.
 92. A liquidcrystal light modulation element according to claim 86, wherein saidregion is formed by partially using a different material.
 93. A liquidcrystal light modulation element according to claim 86, wherein a widthW of said region of the different orientation regulating force and ahelical pitch p of the liquid crystal molecules satisfy a relationshipof p<W<20p.
 94. A liquid crystal light modulation element according toclaim 86, wherein an arrangement pitch L of said regions of thedifferent orientation regulating force and a helical pitch p of theliquid crystal molecules satisfy a relationship of 5p<L<100p.
 95. Aliquid crystal light modulation element according to claim 94, whereinsaid arrangement pitch L of said regions of the different orientationregulating force is not uniform within a range satisfying saidrelationship.
 96. A liquid crystal light modulation element according toclaim 86, comprising: a plurality of pixels arranged in a directiondifferent from a direction of arrangement of said regions of thedifferent orientation regulating force.
 97. A liquid crystal lightmodulation element according to claim 86, comprising: a plurality ofregions which are different in a direction of arrangement of saidregions of the different orientation regulating force.
 98. A multilayerliquid crystal light modulation element comprising a plurality of liquidcrystal light modulation elements stacked together in which the elementaccording to claim 62 is included.
 99. A multilayer liquid crystal lightmodulation element comprising the element according to claim 62 and anelement stacked together with said element and containing liquid crystalmolecules having helical axes extending irregularly in a planesubstantially parallel to a substrate surface when being in the focalconic state.
 100. A multilayer liquid crystal light modulation elementaccording to claim 98, wherein at least the element on the end of thefront side is the element according to claim
 62. 101. A liquid crystallight modulation element according to claim 99, wherein at least theelement on the end of the front side is the element according to claim62.
 102. A liquid crystal light modulation element according to claim62, wherein the liquid crystal exhibiting the focal conic state isliquid crystal exhibiting a cholesteric phase at a room temperature.103. A liquid crystal light modulation element according to claim 102,wherein the liquid crystal exhibiting the focal conic state is liquidcrystal having positive dielectric anisotropy.
 104. A liquid crystallight modulation element according to claim 62, wherein display isperformed by switching the liquid crystal between the focal conic stateand the planar state.
 105. A liquid crystal light modulation elementaccording to claim 104, wherein the liquid crystal in the planar statehas a peak of selective reflection in a visible wavelength range.
 106. Amultilayer liquid crystal light modulation element according to claim98, wherein the elements have different peak wavelengths of selectivereflection, respectively.
 107. A multilayer liquid crystal lightmodulation element according to claim 99, wherein the elements havedifferent peak wavelengths of selective reflection, respectively.
 108. Amultilayer liquid crystal light modulation element according to claim98, comprising: at least two liquid crystal layers having differentoptical rotation directions, respectively.
 109. A multilayer liquidcrystal light modulation element according to claim 99, comprising: atleast two liquid crystal layers having different optical rotationdirections, respectively.
 110. A multilayer liquid crystal lightmodulation element according to claim 108, wherein said liquid crystallayers having different optical rotation directions has a substantiallyequal peak wavelength of selective reflection.
 111. A multilayer liquidcrystal light modulation element according to claim 109, wherein saidliquid crystal layers having different optical rotation directions has asubstantially equal peak wavelength of selective reflection.
 112. Amethod of producing a liquid crystal light modulation element forperforming light modulation by utilizing a focal conic state of liquidcrystal molecules included in a liquid crystal layer held between a pairof substrates, comprising the steps of providing a projected structurefor regularly orientating helical axes of the liquid crystal moleculesin the focal conic state on at least one of the substrates; and a stepof arranging the liquid crystal layer between the paired substratesincluding the substrate(s) provided with said projected structure. 113.A producing method according to claim 112, wherein said projectedstructure is formed by a photolithography.
 114. A method of producing aliquid crystal light modulation element for performing light modulationby utilizing a focal conic state of liquid crystal molecules included ina liquid crystal layer held between a pair of substrates, comprising thesteps of forming electrodes on the paired substrates, respectively;forming a groove on the electrode of at least one of the substrates forregularly orientating helical axes of the liquid crystal molecules inthe focal conic state; and arranging the liquid crystal layer betweenthe paired substrates including the substrate(s) provided with saidgroove.
 115. A producing method according to claim 114, wherein saidgroove is formed by a photolithography.
 116. A method of producing aliquid crystal light modulation element for performing light modulationby utilizing a focal conic state of liquid crystal molecules included ina liquid crystal layer held between a pair of substrates, comprising thesteps of forming on at least one of the paired substrates an insulatingfilm having a groove for regularly orientating helical axes of theliquid crystal molecules in the focal conic state; and arranging theliquid crystal layer between the paired substrates including thesubstrate(s) provided with said insulating layer.
 117. A producingmethod according to claim 116, wherein said groove is formed by aphotolithography.
 118. A method of producing a liquid crystal lightmodulation element for performing light modulation by utilizing a focalconic state of liquid crystal molecules included in a liquid crystallayer held between a pair of substrates, comprising the steps ofpartially forming on a surface, in contact with the liquid crystal, ofat least one of the substrates a region having a different orientationregulating force for regularly orientating helical axes of the liquidcrystal molecules in the focal conic state; and arranging the liquidcrystal layer between the paired substrates including the substrate(s)provided with said region having the partially different orientationregulating force.
 119. A producing method according to claim 118,wherein said region having the different regulating force is formed bypartially effecting rubbing.
 120. A producing method according to claim118, wherein said region having the different regulating force is formedby partially effecting light irradiation.
 121. A producing methodaccording to claim 118, wherein said step of forming said region havingthe different regulating force includes the steps of arranging a masklayer provided with an opening corresponding to said region on thesubstrate, effecting a surface treatment on the substrate through saidopening, and removing said mask layer.
 122. A producing method accordingto claim 118, wherein said region having the different regulating forceis formed by forming an orientation film having a partially differentkind of material.
 123. A method of effecting orientation processing forcontrolling orientation of liquid crystal molecules on at least one ofpaired substrates used in a liquid crystal display element holding,between said paired substrate, a liquid crystal layer including a liquidcrystal material exhibiting a cholesteric phase, comprising the stepsof: forming an orientation film on at least one of said substrates;arranging on said orientation film a mask having a plurality of openingsof a predetermined arrangement pattern, or forming on said orientationfilm a resist pattern having a predetermined arrangement pattern; andeffecting said orientation processing on said orientation film throughsaid mask or said resist pattern.
 124. A method according to claim 123,wherein said orientation processing of said orientation film isperformed by rubbing.
 125. A method according to claim 123, wherein saidorientation processing of said orientation film is performed by opticalorientation processing.
 126. A method according to claim 123, wherein aplurality of electrodes are formed on said substrate, and apredetermined opening arrangement pattern of said mask or said resistpattern matches with the formation pattern of said plurality ofelectrodes.
 127. A substrate used in a liquid crystal display elementholding, between a pair of substrates, a liquid crystal layer includinga liquid crystal material exhibiting a cholesteric phase, and allowingproduction of the substrate by a method comprising the steps of: formingan orientation film on a substrate; arranging on said orientation film amask having a plurality of openings of a predetermined arrangementpattern, or forming on said orientation film a resist pattern having apredetermined arrangement pattern; and effecting an orientationprocessing on said orientation film through said mask or said resistpattern for controlling orientation of liquid crystal molecules in saidliquid crystal layer.
 128. A substrate according to claim 127, whereinsaid orientation processing of said orientation film is performed byrubbing.
 129. A substrate according to claim 127, wherein saidorientation processing of said orientation film is performed by opticalorientation processing.
 130. A substrate according to claim 127, whereina plurality of electrodes are formed on said substrate, and apredetermined opening arrangement pattern of said mask or said resistpattern matches with the formation pattern of said plurality ofelectrodes.